Trainer = LT40

Actually, my first plan was to go from trainer directly to a GP Extra but some have said that it is not a good 2nd plane at all...can anyone confirm or deny this. It would be great if I could go straight to a GP Extra. But I am still somewhat confused....correct me if my logic is off: If the GP Extra .40 is fine for a second plane then the GP .60 should be even better because it will be more stable.....BUT if I continue this argument, then what keeps me from a 1/4 size? I am clearly missing something here....

Thanks,
Chris