RE: 2nd Plane, When?
My second plane was a Seagull P-51 and the only thing that i noticed different from my arrow trainer was that i landed a little hotter. I had actually changed the control horn on the aileron servo out to the point that i could still have a faster roll rate with my Arrow than the P-51. I think a 4* is a great second plane and a SSE with tamed down throws wouldn't be bad either you would just have to use common sense with it.
Flyboy76