Using coloured regs to indicate gas is a polarising topic. Personally, as long as that is NOT the major part of your gas verification procedure, then I am fine with it. Same goes for MOD stickers on mouthpieces and faceplates, etc.Green would match my drysuit.
But then I'd need green fins and a green BC...
Do you guys use color kits for aesthetics or for a meaningful indicator? (Green for 100% oxygen, orange for alternate air source, pink for the tank with laughing gas in it... Etc)?