I had three P-90 RXIs. None of them would start or run reliably. One disintegrated internally on its 10th flight. I went back to a 100 RX. It works reliably, after replacing the fuel pump once. (It would flameout when you pulled the throttle back to idle.). But the 100RX is doing fine now, ...knock on wood.
I have to give great credit to JC and Dreamworks for working with me towards ironing out these issues. My conclusion was the P-90 RXI was not ready for "prime time" for the first year it was sold. Bottom Line for me: I am back to never buying a first year production model,especially turbine! But, ...
The P90RXI had noticeably more thrust than the 100 RX. I kind of miss that extra boost.But, I would much rather have something that brings the airframe home in one piece every time. So I live with the 2# less thrust. One nice thing about the P-100 is it is much smaller and lighter than the 90. I did not have to use any weight in the nose at all to get a good CG on the Sprint. With the 90, I had to add about 10 ozs in the nose.