Two or three sounds about right, but as with most things it depends on the circumstance. I don't go out of my way to buy multiples of the same mold/simple retool but at times the variations do tend to "speak" to me.

Omega Supreme and GADEP are different enough as characters to me for them not to not be the "same." So I have no problem having both (I always imagined Omega having a blank face anyway, despite the cartoon. An impersonal doomsday last-resort weapon).

Then again I have G2 Dreadwing & Smokescreen, Starscream and BB, as well as Smokesniper and Gigant Bomb and while have little or no connection to any of their fictions the mold is strong enough, and the decos are strong enough for me to like each of them.