From my perspective, getting anywhere close to Jerry's nuances in tempo, pick attack, etc... during solos (not that I get close, but trying...) is next to impossible without the forefinger/thumb "scalpel" method. It's the only way I can approximate the same subtle changes in the course of a lead run.
On anchoring: Two things on this... 1) helps keep things controlled, hand settled where I want it. 2) Helps keep arm relaxed, which is crucial. With a gentle anchor in place, upper and forearm can really relax, letting all motion really come from the fingers.
On the pick choice, and its effect on playing: Inspired by Trey and Jerry's big picks, I recently switched from Fender mediums to nice thick 2.0mm picks. What struck me was that it made me play differently, and arguably better. The thick pick allows for some real whalloping of the strings, to be sure. Great, percussive accents a la Jerry. But then if you want to tone it down and get the really soft notes, you really have to exercise good finger control. You can get everything from very soft to very hard notes, but you really have to choose deliberately to get them. That really has opened my eyes to my picking technique, and has allowed/forced me to really sharpen up my playing. Slop becomes more apparent, but good picking is really, really rewarded. Highly recommend the heavier picks to anyone who hasn't gone there yet (which, admittedly, may be very, very few people in the Rukind crowd