rev's will fit...but i dont think they are ADR (i know you are in NZ but i would imagine their standards stuff would be similar) approved...also they are rated for smaller drivers...its only 12inches (30cm) wide at the point where yer butt goes...thats even smaller than the imola's which are 13 inches wide at the same point...i could sit in them...but it was only comfortable for about a minute or so...
if yer a small driver and you can get it approved for road use then i'd get those...DAMN sexy seats...looks wise i'd go them over sprints anyday...
if he reckons sprints are crap safety wise he doesnt know what he's talking about...as for their popularity i can see why they might not be top-wrung...they look ugly until you see them in a car...he's just trying to get more money out of you

also...thats a DAMN awesome price for the revs...they cost over a grand AUD here...