We're using the BC/OW rules for everything else, and we're looking at the rules for Psionics. Seeing as how the work of converting the powers is mostly done already, What we're left with is the mechanics and any issues regarding skills and talents.
Black Crusade changed Invocation from a skill to a Talent (witch removes the possibility of failing the test, bu also introduced potential downsides), and Only War dropped Invocation completely. I am not sure the added bonus to the Focus Power tests is needed, to be honest, but I wonder:
How to handle the exisiting skill? Convert to a Talent, and return any spent XP on Invocation +10 and +20 to the Psyker? Keep the test as-is, and let a success grant +1 PR?
Corpus Conversion was changed in BC, and I like it. OW dropped it, presumably because Sanctioned Psykers aren't supposed to be doing stuff like that. But we all know the Inquisition attracks people who, ah, think outside the box so to speak. So… Use the BC variant as is?
Psychic Supremacy. This was also an issue with Ascension. The Fetter rules pretty much make this Talent obsolete. Refund XP? Require to be able to Fetter? Personally I think it madness that the Psykana would sanction any psyker before he learnt to Fetter, and believe the OW approach is the right way to go: Use it from day 1.
Discipline Focus, Mastery and Power well. All these reduce the threshold or add to your power-roll somehow, and do not exist in BC/OW. Discipline Mastery adds +5 to a powerroll, and translates nicely into a +1 PR. But Focus and Powerwell both add just +2. Suggestions?
Any others I may have missed?