maybe this discussion is done, but here's my 2 cents on the Russian vs. American swing.
whenever i did american swings, i would feel my shoulders rubbing in very bad ways while overhead. in general, if you have both hands on a KB, then the grip is going to be very close. combining that with the effort needed to throw the KB back down from the max height, this would aggravate my shoulders greatly. because the grip is so close, my shoulder would squeeze against my face when the bell went overhead. my shoulders would naturally get pushed by my jaw into bad positions.
when i perform russian swings, i feel that my shoulders are doing no work. when doing snatches, i feel none of this either (except for when the catch finishes obviously). on the other hand when doing the american swing, i have to use my shoulders more just to stop them from hurting.
i guess the last issue that arises is whether you could just do your american swings with 1 arm or with 2 kb/dbs. once you take it to the single arm domain, i feel that the snatch would just feel more natural to begin with.
from an argument of power output, there's other ways to increase it without resorting to american swings.