I don't know how New Coke was, but I can tell the difference between Coke and Pepsi any time. I could even tell you when you're giving me a mix between the two.

I prefer Coke Cola as I indeed drink larger quantities, but my wife prefers Pepsi. And I don't mind Pepsi, but when I tried Pepsi Blue, the taste was so awful it was nauseating, although I did like the commercial. And if they gradually migrated old Pepsi to Blue, I don't know if I would notice what's going on, but I would stop drinking it.

IMHO taste matters.