I just completed my Ultra Sport 40+, and finally fitted an OS 50 (instead of the Saito 100, I mentioned I was going to use, in another thread - I chickened out!), and it's one of the best fliers I have ever had!
I fitted retracts and, unlike the usual problems with warbirds etc that have retracts, it doesn't suffer from bounce when you land. It just flops down in a very controlled way and glues itself to the runway!
Good luck with your completion of yours. You will lurve the way it flies!
-David C.