I do hack squats instead b/c my knee sucks--I don't care what anyone says regular squats can hurt your knees. I'm the most anal person I know about form, too. Anyway, I've had good gains with hack squats. Just use a full ROM (Butt to the floor!!) and I don't notice much difference. In fact, I'm less worried about using full ROM when I'm hitting those last hard reps, so I may even be getting more out of it, personally.
I'd guess deads with the trap bar would be more of a squat....but I don't use it, so I can't say. I'd stick to the good 'ol deads with the barbell to the front. Otherwise, it seems like you'd only have a 4" ROM in your lower back when you do 'em with a trap bar.