I got the white belt, if there is a difference, it is as close to no difference as can be from my 1-year-old Needle Doctor Rega replacement belt.
I bought mine from the Analogue Seduction ebay link, like Frank and xyyy--it arrived very fast. Like Frank and Safe1, it was more of an off white, although if it is true that the rubber is not "processed", then I wouldn't expect a pure white or any uniformity of "color/non-color".
I'm still listening right now, going through Elvis Costello (Imperial Bedroom), CSO/Solti (1812 Overture), Gregory Isaacs (Night Nurse), John Coltrane (My Favorite Things) and Moody Blues (Days of Future Passed). It is certainly no worse than my old belt. I might be suggesting things to myself that perhaps the bass is ever so minimally slightly more defined and lower, but since changing belts doesn't really make for easy A/Bing, it's merely ear memory at this point. Also, there is definitely less wavering in "Tuesday Afternoon's" violins, though I wouldn't put money on whether this is a definite effect.
I will point this out, though: I have an aluminum subplatter on my Planar 3. That, by far, made the biggest difference of any change that I have ever made to my turntable--anybody could have heard it. I have a Super Elys 2 that replaced a 15-year old Adcom Moving Coil--anybody could have heard that difference. I have a Musical Fidelity V-LPS with upgraded power supply which replaced a Bellari Rolls VP129--that made a significant difference that can be heard on most LPs.
White belt, at least on my setup, is no different than a standard replacement belt. Perhaps on the original subplatter it does make a difference. I'll be keeping it on and am otherwise satisfied with it--just it is certainly not a game-changer...