I should mention a buddies experience with his first OS 40cc gasser (4-stroke). He had a lot of problems with it initially which turned out to be operator error and some setup issues. After he figured it out he absolutely loves the engine. Its just a bit different in operation and setup. Sounds great too. You might run into the same scenario, just stick with it and you'll get a lot of help here and eventually figure it out if there are problems.
Edwin
Yeah, my whole fleet is slowly converting to gas. I have one of the EVO 15cc to try out on a TF Corsair.