I had a nexstar. While I liked it, the landing gear snaps in and a hard landing can make repair somewhat of a pain. If I were to do it again, I'd definitely go with something in the 60 size. More power, easier to see, and larger models generally fly better than their smaller counterparts. Then you also have a 60+ sized engine to move into another model when you're done with the trainer.

If you're learning, you don't want to putz around tuning an engine. That is the single most frustrating thing you'll encounter when training aside from crashing. I'd highly recommend an OS engine when starting out. Once you get more experience, then play around with the cheap stuff from China.

The other thing you might also consider is an electric. While more expensive up front than a simple glow engine, you'll never worry or deal with reliability issues or dead sticks.

I'd check this combo out with an OS 75ax:
http://www3.towerhobbies.com/cgi-bin...?&I=LXJ558&P=0

Lots of part available for your trainer and $60 off $300 a or more order if you join their saver club.