The biggest drawback is the engine. Pull it out and put a decent motor in there eg SR20det
*hides*
Have a closer look at mine on the way back from wakefield on Sat
*To answer some of your other Q's, the diffs are the same - I swapped my Cefiro and Sil80 diff over the other week as the mech is better off in the track car.
*Suspension is same (including castor rods) - yet to determine if sway bars are same
*Cradles and rear arms are same (so s13 pineapples/alloy bushes fit fine)
*Seat rails are same as R32
*Front brakes are same as SR20DET S13
*S13 front strut brace is same, and R32 rear brace is same
*uses mechanical speedo like R32 rather than electronic like S13
*Sr conversion is easy peasy
They drift real nice