I got as far as the psychic rules in 2e and haven't finished reading.
I tried converting 1e characters with 2 players I have and we didn't finish we ran out of time before we got to spending xp, which I'm glad about because the whole process of aptitudes and flipping through charts and pages - per player - to spend those points to build your character is ridiculous. To say nothing of the poor psyker player who will now have to come to terms with a dreadfully subpar psyker system and a choice of crappy powers none of which represent the stuff he used to have (none of which were particularly spectacular or over the top either).
They charged £20 for people to buy into a playtest process and this is what they came up with? A rule system so convoluted it is barely any different from 1e and, again, leaves no room in the rulebook for important stuff (like more than a couple of crappy vehicles) including a decent bestiary/adversary section.
I despair. The psyker rules are utter crap. There's no other words for it. What on earth possessed them to come up with something so fundamentally stupid? Why do i have to work with a character creation system so arcane that only the most die hard ffg fanboys and/or 40k players will perservere? YMMV but i have to believe this is all some terribl Chaos plot. None of this makes the slightest sense. No game needs 400 pages of rules. It just doesn't.
There's so much in this post...ugh.
What do you find wrong with the psyker system?
How much time did you have? Like 30 minutes? Conversion is difficult, it's best to start from scratch of the core concept and rebuild that way anyways. You could always have made a note card of the aptitude cost to cut down on time too.
Again explain why they're subpar.
It is extremely different than 1st edition. What's important to you? What makes the vehicles "crappy" and the bestiary/adversary section less than "decent" to you?
There are other words obviously as you keep going on.
There are plenty of games that have 250-400 pages, need is a subjective think that gets decided. What you think the system needs isn't what they thought it needed.