Just the FYI part, 20990 is the Warn part number for the Premium.
You may already know that, since you found out the 9790's are the standard (which I like better by the way), but figured I'd throw that out there just in case you were still looking.
I don't know what the real differences are inside them anymore, but I agree, that they look very similar where the little splined collar is concerned. Hope it works out for you.
Paul