Why not try a pattern plane. They usually fly as fast as a Ducted fan model. Don't know much on pusher prop models but I know a good pattern ship will help you get aquainted with the speed aspects of flying a ducted fan among other things.
As I see it, the only thing different between the pusher and a puller is that you have prop wash going over the wing surface helping generate lift. With the pusher, you have to get up to airspeed first before you can fly. I'm building a pattern ship right now. I have the basics down but need something a little faster than what I'm flying now.

Tamecat