The other thing that I have only ever seen taken advantage of once is that in a game where Cash to Karma is active, a player could easily pay a the team's wizard to quicken a spell on him/her. I have only even seen this done once in a game I was involved with. But every time a caster gets quickening I'm interested to see if folks catch on to this. Have you guys seen this?
As much as Quickening is opening its self up to getting regulated by the GM via NPC reactions.......
Quickening another character is going to be SO much worse.
Wherever that guy goes there is a little astral thread leading back to you. No Thanks.
That said, my current fun joy is to get together with the Mage & the 2 of us temporarily buff the Troll-Adept w/ Intuition, Combat Sense, & Invisibility.
Do you have any idea how much carnage a Shotgun/Combat Axe Troll can do when the enemy can't see him & even if they do he's dodgy as all hell & then when they finally manage to hit him the Troll has like 28 Soak dice. Yeah, its a lot

We can just hide outside & let him kick in a door solo. No Mage fireballs, No Mystic Stunballs, Just a Troll running around like a scene from Planet of the Apes crushing those damn dirty humans.
All the time. It's not a big deal, in my opinion, as long as the player's actually play their characters (aka, don't just give 10,000 nuyen for a 5 Karma quickening; it's going to cost 20-40k for it). It's part of business, and the mage has to be willing to risk their spell being detected and traced back to them, at some point.
Also, totally unrelated, but my favorite use of Quickening is the Shapechange spell. Turn into a cat or something, spend 1 Karma to quicken, say goodbye to the rest of your life as a metahuman.
That is a huge risk that I don't see most mages doing honestly.
Say goodbye to running from the law & hello to running from the local Chinese/Mexican restaurant.
