The 4* is very similar to the Bingo I have. I use a OS.91 Surpass on it and love. I think the OS is easier to break in than the Saito but both are in my hanger and both are excellent engines.

I have not flown a 4* but I can asure you that the Bingo's flight envolope is manuverable enough to use as training for a bipe so I see no reason the 4* would not be the same.