For completeness' sake, I have to say that my group really didn't enjoy Dark Heresy at all. The combat rules were long and fiddly, resolving damage was a huge pain (determine if hit, roll damage, figure out hit location, check armor in that location, subtract armor from damage, apply damage to wounds, if put below zero wounds, cross reference negative wounds with damage type and hit location to determine special effects... oh no, his ammunition exploded? Go back to step 2, but for everyone in a x meter radius), and the success rate on most actions was a bit too low (ideal success rate in an RPG is about 70%. We were averaging around 45% for a reasonably-high ability score, then maybe +10% for skills and +10% for gear... in things that we had optimized for. For stuff that we weren't particularly well equipped for, not skilled in, or didn't have a high ability score for, failure was basically inevitable. Granted, we were just starting characters, but the game felt like a comedy of errors).
So I have to give Dark Heresy and related a down-vote. Maybe that's what you're looking for, though (and Deathwatch and Rogue Trader probably take care of the low success rate issue, since they start you off at higher levels than DH does).