I have been flying this model for over a year, with an OS50SX. It hasnt got indefinate verticle by any strech, but it's taught me more about aircraft control than anything else. The Saito 4 strokes would be ballistic, but even with the 50SX I had to add weight to the tail. Don't get me wrong, I'm all for overpowered aircraft. This is the only plane I own with less than about 1.5/1 power to weight.

Hope this helps
Greg