E-Revo that uses clutch set up?

I am in the market for an erevo and located one, but the seller says that it uses the tekno kit that uses the clutch set up from the nitor and not a pinion gear? I am a little confused as to what this means as far as performance, maintenance? What would it take to convert it? Also it has the FOC, what would it take to get reverse? Any advice is appreciated!!