This is a little long, but I thought I would weigh in on this in case any of my thoughts help others see a positive to this approach to knowledge skills, because it actually checks a box for me with what I want from a new edition.
There was a question of how much a character knows in an unranked skill system. I find that an easy answer, personally. Here it is. This is a game world where the whole of the Matrix is accessible via your commlink. You have super google, quite literally at your fingertips. A decker (or anyone) could conceivably even have their commlink's audio and contact's video sensors grabbing keywords and searching relevant terms and images live as they occur from context clues in the environment. Everyone can be at amateur "shadowgoogle" levels, and I assume that trivia level knowledge about the game world is omnipresent. So , as a contrast to that, the investment of chargen resources into a flat skill means the flat skill already automatically exceeds that default level. So they are not amateurs or dabblers. They know their stuff.
Could they have earned a PhD level degree in this at some point? Sure! Can they harness that degree of knowledge at this stage of their character's life? Spirits NO! Why? They are shadowrunners. Their existence is defined by living illegally in a world that they have to fight to survive in moment-to-moment. They have old enemies, treacherous Johnsons, random paracritters and gangs, social upheavals, Lone Star raids, and all manner of other things to deal with, and that was just Tuesday. That's not an environment where you can stay in tune with the latest discoveries and greatest theories, tech concepts, etc. Not enough to stay at those levels constantly anyway and keep them top of mind at all times. If SOTA is moving as fast as SR presents, what you knew last year is now old news, plus the soykrill is getting low and your last trip to Stuffer Shack ended in a Food Fight. You have Serious Trust Issues eating up your cognitive bandwidth everywhere you look. You won't lose the fundamentals, but nor will you always be up to speed or sharp enough to grab every salient detail you otherwise could if you had a less hostile lifestyle. So, you are not a functional master of any subject either (by comparison to an Academic glued to the trideo and Matrix all day). So you fall somewhere between "better than Shadowgoogle" and "distracted/lapsed expert". That's not an unreasonable place to drop people in a system that handwaves specifics to the degree that 6e does. It's also why you can't always pass a skill check even with a +2 bonus. You just can't pull it out of your fanny in that specific moment, even with your PhD. However, you didn't forget the fundamentals, nor are you an ignorant hack. The GM can ensure that feeling just by handwaving away a need to roll in some cases. In doing so, the GM can create a level of allowing the character to feel special and have the choice be important. You knew about an aspect of the mission that others did not. It just happened because you put the points into that area. Now those points mattered more than Elven Wines 5 or Seattle Gangs 2. I can still do that same thing with a system with ranked skills, sure. It doesn't mean a big change for me in how I leverage a knowledge skill in a player's favor. I want them to know things. I want their investment of points/picks to matter.
Now, all that said, maybe a static bonus may still not have the feel you want. To me, here's where the context of the skill is more relevant. I would find out from the player how and where the character acquired their knowledge skill. Depending on the backstory, I might be inclined as a GM to give even more of a bonus. Here's an example. Player is meeting with an NPC that loves computer theory. The player character also has that skill, and needs to convince the NPC to agree to be extracted. They engage the NPC in banter about said subject. The player has already told me the context they learned this skill in happens to be at a university, and that the character earned a degree in it before having to flee to the shadows. In this case, the backstory to the NPC happens to be similar. The player's character can not only talk knowledgeably about the subject, there are personal connections for both characters. In this case, I might offer the player a bonus to their social skill to convince the NPC. I might lower the threshold required or maybe just give the character a +3 bonus instead, whatever feels right for the scenario. By contrast, a character who instead learned the knowledge on the street has a different context, and tends to know a bunch of jankity shortcuts, and while on the bleeding edge, is a little less likely to appeal to the high-mindedness of an academically grounded researcher like my NPC. For an archetype, think Kaylee Frye from Firefly. The context doesn't align, so I wouldn't give exactly the same bonus. They can still dazzle with acumen, but the flavor may offset it slightly.
So, I view having an unranked skill base be an asset to improvise around.
Next area of concern I saw expressed here was how to test with it. Rules unseen, I would also default to the context here too. If the character is trying to recall it from their studies, roll for Memory, add the +2. If that roll fails, they can't recall, BUT they would certainly know where and how to search on the matrix, so make that test instead, still with that +2 bonus. If that crapped out, its time to ask a like-minded contact in that field. Now its a bonus to the social skill test or maybe the contact uses their skill check instead for that subject. As mentioned previously, using Perception to spot details that the character would pick out, also a good option, but basically any excuse to bring it into play is a reward to the player's choice.
I would also try to make this feel distinct from general 'shadowrunner' knowledge, which I credit all characters with having. The player won't usually know the world very well, so I provide it by starting my answers to questions (or providing guidance) with "As an experienced shadowrunner, you would know (x)". I would also apply that same logic when providing a reveal with a knowledge skill, as the rules apparently will also suggest. I credit the character with baseline helpful ideas as starting points, so the player has something to run with. When I look back at times players made horrendously bad choices, many times it was my failure to educate them on consequences. Other times, they just really wanted to shoot the Space Needle with a rocket launcher. That's probably also on me for letting them get that bored, though. Or we were all just 19 and squirrely.
I digress.
On the flip side, where I would draw the line is at insider knowledge. So, just because you have the Ares Macrotechnology skill in no way means that you will know the guard rotation at the facility you are about to raid. After looking at the context the player has for the skill, I would provide the default reveals I am comfortable with providing that don't give away the surprises, but yet also tease the player into thinking ahead. They wouldn't know any old passcodes, but they would also be aware enough not to try one anyway. To get insider knowledge, they have to do legwork and/or hit the shadownets to see what they can dig up. That's always a side quest level event.
So to me, a flexible skill, further defined by character concepts and background would drive the resolution, help set the tone and reward the backstory. How I use the skill with player A also gives the clue to the other players that they should add some depth we can play off of. Now they are all thinking how it is that they came to know about Elven Culture and why the character likes their wine so much. When it comes around to be useful, they get a very personal reward from it (if I did my job right). Seeing how I'm using it, that side quest for insider knowledge can now serve to cause other players look at their sheet and see how they can help. Maybe the social intel they need is with that NPC who loves Elven Wines. (As the GM I can also just make that true, if I want to further provide rewards, and that sounds like something I would do if it didn't feel too ham-handed in the moment).
One thing I definitely hope for though, is better guidance to players in this edition for where to set the breadth of knowledge. That was part of my turn off to the way 4 and 5 did it. I suppose, since the default knowledge level is "somewhere in the middle", that's where the skill breadth should land too. I shouldn't allow "arcana", but "hermetic arcana" is fine. Conversely, "magical foci" is probably too narrow. Somewhere in the middle is fine, and ill-defined is good, not bad. There's your TL;DR takeaway. I hope these thoughts were helpful to you as players and GMs.
