This, basically. I'll tell ya what man, I've played around with a lot of rep ranges... 20-rep squats, super high-rep (20+ for pumps,) 5-8, all sorts of stuff.
I've been finding that doing 3 sets on the hack squats is giving my legs the most bang for my buck. My first work set will be at a weight that I'm aiming for for 4-5 reps. My next set will be aiming for 8 reps, and my last will be aiming for 12. That way I'm getting the best of both worlds, and decimating my legs in the process.