I have number of Pink ones and they have subtle differences. I would say that the run will affect the stability more than color.I have a decent collection of Opto Pures. I'd rank the relative stability of mine as:
Opaque Neon Yellow-Green >> Opaque White/Pink > Clear Orange/Blue/Red > Clear Yellow
I suspect that non-Opto Pure throwers might not notice a difference. I like the opaque neon yellow-green ones for dead-straight flat shots out to ~250; can't really say they fade but they will do a slight left curl on hitting the ground.
Are yours with weight sticker or engraved?