RE: Nitro trainers...
The Tower Trainer is an excellent choice. Both of my sons learned on one. I learned on the Hobbistar 60. It is also a good choice. It will carry you a little futher than a trainer with a flat bottom wing. It's not exactly a second plane. Maybe a 1.5 plane. It is very forgiving, flies slow, lands like a trainer, but has a semi semitrical wing with not so much dihedral. It is a little more aerobatic than the flat bottom trainer wing. I'm sure there will be many opinions given. What ever you decide to go with just be sure to use an instructor.