I haven't done a lot of these but I have recently used pistol squats as part of a program. It's complimentary to some compounds, bounds and ghr's. I have long goofy limbs so a full pistol is crazy hard for me. So I always use a hand on a low object to assist on the eccentric. Then at the bottom I pause 1 sec, remove the assistance (hand) and explode up. I move up fast and end up jumping a few inches just from momentum.
I've found doing them this way is awesome. Even if I could control the eccentric easier not sure I would. There is already plenty of eccentric work in the squats, DL's, lunges and ghr's in the program and the assisted eccentric pistols give me volume and explosive movement without the CNS fatigue.