The direct and accurate answer to your first question above is a T-6, most any will make a lousy trainer and considerably increase the time for you to reach any given level of skills.

Most classic full scale trainers do indeed make for very poor RC trainers and this includes any Cubs that are anwhere near scale. If you insist consider this: The AT-6 was 'not' a primary trainer period. It was an advanced trainer intended to be used only after the student progressed through primary and basic trainer (types) steps.

Now to your second question above the answer is no that experiance will not directly help you other than knowledge of how an airplane flys. Indeed it likey will increase the time to acheive any given level of skill. Full scale pilots fairly consistantly take the most time and are among the more difficult RC students on an average.

I am not just talking out the hat as a very active full scale instructor in fixed wing, single and multi, instrument and rotors as well as gliders since about sixty four untill my retirement ten years ago. In addition I have also mentored many (I hate the word instructor) into the RC world since well before the development of proportional RC.

Excluding of course knowledge of FAR's, navigation and Weather it is an easier task to train an experianced RC pilot on full scale than to train an experianced full scale pilot on RC.

To some up the T-6 thing I beleve especially since the ARF age is the overpowering compulsion to not be seen with a trainer but instead use the most inappropriate types possible for a first airplane, is in fact the number one reason (agine my opinion) for a very high failure rate and broken dreams of RC flight.

All of the above is only just my opinion

John