I agree that you should keep your trainer. There are a lot of good reasons to have an "expendable" airplane. If you ever crash your plane and you think the radio works ok, then put it in the trainer after you've tested it and find nothing wrong. If you ever send your radio in for repair, then put it in your trainer to check it. Ask how many people have had radios repaired that came back and didn't work.

It's good to have at least one plane around that you don't really care too much about.