So, I started a second playthrough last week. This time, I made my RT a psyker and tried to use mostly custom characters (except for Heinrix and Argenta).
And...now I've abandoned it.
I was running a party with three psykers and, without Cassia around to help manage Veil Degradation, shit goes south pretty quick and you're suddenly fighting multiple warp demons on top of already difficult bosses.
So, now I've started another playthrough, again mostly with custom characters, but this time I'm focusing mostly on ballistics. I still have multiple psykers, but now I'm using them for occasional buffs instead of offense. (Speaking of which, that one divination staff you can pick up at the prison colony is kind of underrated--guaranteeing a critical hit against one enemy for 0 AP is quite good, especially early on.)
The difference is pretty night and day. I was even able to win the first Chaos Space Marine fight without too much trouble.
However, did the new patch break turning in space combat? Very often now, when the indicators on screen say I'm going to turn 45 degrees, I end up turning 90 degrees at the last second. I don't remember seeing this during my first playthrough and it's really damn annoying.