I've used Cobalts on mine since they came out. They definitely make a big difference on the smoothness of the tone from string to string and the low B rocks
Not yet but I plan to. Right now I have the preproduction Cobalt flats on a Stingray and a Bongo fretted and fretless. Gotta wait like everyone else .
Hah! I overlooked the "flats" part of the question.
I have the regular Cobalts on my Reflex but I have a set of Cobalt Flats on order for my fretless Bongo.