i've been listening to my e500s with the black foamies for about 20 hours, and i can say that they do seem to put a slight veil on the treble. they do seem to boost the bass impact over the clear flex PVC and the old yellow foamies, and midrange detail still sounds superb.
comfort-wise, they're as comfy as the comply tips, although they don't lose that bass impact, which i think is a good thing. the finish on the foam seems like it'll keep them looking pretty new, although they are black so dirt won't show. the isolation is better than the foamies, and i think might be better than the clear flex. as far as longevity, someone here said they've been using them for 4 months, which is probably 8x as long as the foamies lasted, on average.
all in all, a much better investment than the comply tips (for me anyway). i have 2 pairs of comply tips that will probably never get used ever again.