Odd topic you linked to. I didn't get the point of it all. Those posts are weird.
I never heard of "mixing bittages", but seeing as how some Capcom characters like Morrigan are reused game after game, being not that much different between generations, I don't think that's really an argument with any kind of validity.
(I like to use Morrigan in Capcom Vs. SNK 2 EO despite her being the "pixellation queen".)