OK, but you can take more negative metagenic qualities if you want, so say 20:20 is also alright?
The short answer is going to be:
Nothing really horribly broken happens. What this means is that there's no 35-point limit on PQs, so some PQs that are normally marginal are usable, and that you can take more PQs by taking balancing NQs.
You will need to be willing to actively screw with people in proportion to how many NQs they have, because as I'm sure you know, not all NQs are made equal. I don't think you can go all that high without involving a certain amount of stuff that's easy for a GM to bring up, though.
The main things that will happen are:
Mages and Mystic adepts benefit a bit more than everyone else. Non-awakened characters who don't want Martial Arts benefit less (they are going to want less PQs in the first place). PQs that are in theory good but take up too much of the 35-point budget to be useful are now useful - this is mostly just Type O System, and to a lesser extent Adrenaline Surge.
Some PQs that are less efficient than stats are now viable; for example, Focused Concentration, if you are willing to balance them with NQs.
Letting people get all the PQs they want isn't actually abusable. The only place it is abusable is going to be people taking large amounts of NQs. You can't have more NQs than your PQs+35, most people will easily have at least 15-20 points of PQs that they want anyways, and some characters will have way more than that, so the main limit is going to be whether you are actually willing to tolerate the drawbacks of that many NQs. Also, some NQs that are normally worth a lot of points but are really horrible are at least OK without the 35-point cap and with a lot more strictness on the easily abusable NQs.
If I wanted to try to abuse this - assuming that I thought the GM was actually going to enforce "fuzzy" ones that come up at the GMs discretion - the obvious options are:
There's a truckload of NQs that call for Composure tests to ignore, and a piece of 'ware buried somewhere I forget that drops the threshold for composure tests by 2. Combine that with a decent Willpower+Charisma, then take ALL of those composure-test NQs. There's enough of them that you could easily rack up an enormous pile of points - way more than needing to not glitch composure tests is worth. I would suggest just editing that piece of 'ware to not work on your qualities, only on other sources of composure tests.
You can probably stack on a whole ton of metagenic NQs that boil down to "you are freaky looking." Being freaky looking is a legit drawback. Being freaky looking for 20 different reasons is not 20 times more of a drawback. There's various ways to fix this.
Lastly, there's some individual NQs that are a problem - not so much with a 35 point NQ limit, more so without.
-Incompetence (things I sucked at and am unlikely to need to personally do)
-Impaired Attribute (if you weren't going to softcap an attribute, this doesn't mean anything to you)
-Betel addiction (unlike other addictions, you can't ever go beyond Mild, no matter what, and it's cheap and legal).
-Codeblock (a shitty matrix action; only hackers can take it, but there's a ton of matrix actions that nobody cares about anyways)
-Scorched - the book explicitly says it's worth 5 bp even if you aren't a hacker/techno.
-Sensitive Neural Structure - ditto
-Sensitive System on people who weren't getting 'ware anyways; it's not a problem when it was "where are your 35 NQ points coming from," it is when it's 15 free points to not get 'ware.
-Distinctive Style. 2 levels is a legitimate drawback. However, levels after 2 are cosmetic - but still give points.
-Hung Out to Dry on characters with no contacts. Yeah, it's probably not a great idea to have no contacts, but...
-If you belong to the "In Debt doesn't have to be bought off with karma, you just pay the loan back" school of thought, it's a problem. Otherwise it isn't.
You can sorta fix these with an "if you take it, I'll force it to come up" policy - for example, "if you take Sensitive System, your character will be forcibly implanted with cyberware," "if you take Scorched and aren't a hacker, plot contrivance will force you to hack," etc. If you are actually willing to do this, none of these are problematic, although I'd suggest being upfront about this with your players. Personally, as a GM, I don't like things that force me to constantly contrive plots to make them come up, but YMMV.
Otherwise, I would suggest spot fixing all of the above. Do require In Debt to be bought off with karma, don't give points for Hung out to Dry with no contacts, don't allow points for 3+ levels of Distinctive Style (or, alternatively, uncap the drawback), only allow Mundanes and Adepts to take Sensitive System, only allow Sensitive Neural Structure and Scorched on hackers and technos, make a "short list" of acceptable Codeblocks, make Betel Addiction 0 points, ban Impaired Attribute, and be really strict about allowing Incompetence.