MK XII "adapted" sets
 

Are these simply enhanced sets you can purchase at tier 5 reputation?

I'm confused as to why someone would select the regular version. Just price, or are there other requirements for the adapted version?

The adapted sets are the opposing factions sets.

Fed adapted set is basically a K.H.G. set for the Feds while the K.D.F. adapted set is basically a M.A.C.O. set for the K.D.F.

They also unlock new costume varients for the ground sets too so Feds get a new M.A.C.O. costume and KDF will get a new K.H.G. costume.