I think Dan Martin liked the black stuff just because it was black. I don't think there's any problems using it for the lower oil pan (where there is low torque on the bolts). I don't think his engine has seen oil yet though.
The Ultra Grey RTV is supposedly designed for mating surfaces with high torque on the mating bolts like the upper oil pan and a few other places. I think Nissan just figured it's good enough for that, it's more than good enough for everything else. Why bother telling people to use two or three different sealants when we can just recommend one?
Anyway, what's your problem with Grey RTV? You allergic? =]