Had PB with black and grey filters bought separately.
To my unsophisticated ears differences in sound between filters are rather subtle, especially between greens and blacks. Vs blacks greens bundled with PB result in a signature that's somewhat more smooth, warm, with a little more bass (still anemic to my tastes) but at the expense of some detail in highs and maybe a little less forward mids and a bit narrower soundstage. But it's all splitting hairs unless you are a bona fide head-fier.
Compared to both greens and blacks grays are more unique, but still well within same overall sound signature. To me grays sounded with most detail and clarity in mids and highs but with the least amount of bass. Still if you are into "neutral, balanced, uncolored" school of sound and corresponding music which isn't "un-balanced" by definition even with grays bass should be enough.
No matter which filter sound sig of Audeos stays more or less the same at its core - polite, balanced, detailed, forward, non fatiguing, no excesses, with rather intimate and shallow soundstage. Not really satisfying and fun to my tastes but technically I guess great.
Oh and another tidbit. Audeos are relatively inefficient out of iPod/iPhone and actually benefit form the amp (at least from my stationary Creek OBH-11). But to me gray filters seemed to be a bit easier to drive than greens probably because of the need to move less air.
