I have a Quaife in my 205 and find it excellent. Seems to work well under braking and accelerating out of the bends as well as keeping the car in line mid-corner. Although I can't compare it against much as I haven't tried the plated ones. Personally, I avoided them due to the maintenance required - the Quaife is fit and forget although I would expect you get slightly better performance from a plated diff (such has the TranX or Kaaz ones).

I don't think there is much need for anything more serious than the Quaife in a sub 200bhp trackday car, maybe a racer could tell the difference but I probably couldn't