Ho-ho, Vancian cave wizards, here we go!
edit: early impressions: You need 8 slots to be the reasonably attainable max, not 6. You've got 8 skills per psi school, and it isn't even thematically consistent to restrict beyond that. I get the mechanics for how you're limiting psi generalists - and who knows, maybe it'll end up being a fun new way to go instead of the mistake it looks like right now - but you aren't just controlling psi options with 6 innervated slots, you're limiting beyond mere single-school specialization.
I think 2 slots + 2 per 4 Int would be a better number without ever feeling like there's no sacrifices that need to be made. Still would require 12 Int to unlock all the slots so you couldn't have 18 Will *and* all the spells, but it would allow pure psi to roll out the gate with 6 slots and pick up their eighth by Depot A, which is when you really want newer players to have as many options available as possible.
I do like the psi points and psi reserve. That feels like a pretty good resource management tool. Not sure I like wiping out both the psi pool and the reserve when switching innervated slots, though. Seems like the pool should empty then refill from the reserves. But if those inhalers are more common than they first appear to be, it won't really be a problem either way.
As a general statement, though, I hate it. The real joy of psi wasn't the power, it was the ability to try out nifty things and expand replay potential. Congrats, you've gimped psi into a one-trick pony and ensured that we'll all just be cheesing the same techniques again and again. If this is now the next game handles psi, I definitely won't buy or play it.
second edit: You need to do something for poor Psychosis. This psi change isn't bothering Tranquility builds nearly as much. Maybe keep the increased psi cost for Psychosis but give it a psi reserve leeching effect so that the long-term costs come closer to balancing out? When there was no global accruing resource management metagame Psychosis only had to worry the immediate psi pool considerations, but with crit chance being non-deterministic Psychosis again gets the shaft with increased total costs, thus increased global costs, and a benefit gated by RNG.
I do like the new resource management and how it forces non-psi use regularly; but, man, poor Psychosis builds.