I've played with tactile greys and they're interesting. They're stiffer than stock Clears, but don't seem to have the steep ramp-up, more like stronger black springs. The tactile bump is a little less noticable than Clears due to the stronger spring, but still quite a bit more noticable than Browns.
Personally, I wouldn't want to use a full board of them, due to the stiffness, but if you like really stiff switches they're good.
My favourites are 62g ErgoClears.