As I've previously blathered about in my vlog, I'm somewhat on the fence about published and licensed settings. One the one hand, it gives people an additional way to get into the setting and get a handle on what it's like. On the other hand, it can be limiting ("That's not canon!") and can be off-putting to those who haven't played in the setting before or aren't as familiar with the source materials.
Now, as it happens, I own several of the WH40K RPG books (Dark Heresy, etc.) and part of me would really like to run a game, but I worry that most of my players are not up to speed on the 40K universe. Mechanically, it's similar enough to WFRP that I think they'd catch on to the rules quickly enough (several of them played in a long Marienburg-based campaign), but it's the fluff that has me worried. Warhammer and 40K are so much about the feel of the setting that I'd really want to get it right. I don't feel it's fair to hand out reading lists, etc. but some understanding of the setting seems pretty important, IMO.
Have other people run into this sort of thing before? How have you handled it?
*I highly recommend Abnett's books. The man can write!
No, you can't play an elf!