Finger control is good for just about everything except raw power, although there are some guys (Aronoff) who can get unbelievable power while using the technique. I think this is a better pursuit by studying finger control in its entirety and not just for a few applications.

Closed or buzz rolls, to me, are defined by the ability to control the stick and the skeleton pattern you use. Whatever technique you use to achieve this is probably fine assuming it isn't tripping you going into or coming out of the roll. I've know a few guys who can't do anything coming out of a closed roll because their hands are stiffened up. That's not helpful.

I got a lot of help with finger action from Art Verdi's website www.artverdi.com   Lots of finger control vids