If you are like most of us, you will end up keeping the trainer and getting a true second plane. There are two thoughts on why.

First, you will always have a backup plane... just in case.

Second, most likely you will go back to the trainer and fly it, just for fun, and to get you back to basics of RC flight.

There is also a third one, but this is more up to the particular pilot. You may want to train someone some day and you will have a ready package to do just that for the person that does NOT have his/her own trainer. I've gone through that. I sold my Nexstar about two years after I solo'ed to someone that destroyed his trainer and needed one that he could just fly and not have to pay a high price. The guy was not working and had limited income (he was out of work because of a medical problem that he developed). So, I sold him my Nexstar for a real rediculous price.. but it was worth it.

Aaanyway, last year, I really wanted to get back to basics (see #2 above) AND we needed a club trainer, so the LHS gave me an excellent deal on a Hobbico Super Star RTF trainer that I still have, and still fly on occasion. It's fun and, as I said, gets me back to basics after flying some of the 'easier to fly' advanced stuff. (meaning, they fly straight but you HAVE TO FLY THEM, not glide when you feel threatened by mistakes). And, I've had several people up with it so far as an introduction to RC, using the buddy box, of couse.

Anyway, this is just a suggestion based on my several years of experience.