I recomend staying away from four strokes for your 2nd plane. Maybe even your 20th.

I've had a few saitos but i have found that i am happier with the good two strokes. Fewer dead sticks, lower cost, far less vulnerable to crash damage. It is hard to get a saito to idle less than 3000 RPM without adding glow driver. They sound more realistic, but are a real pain.