chipmonk--no.
You said you don't want something you'd be bored with after three months. Consider yourself lucky if your trainer lasts three months. Most people who "still have their trainers" actually have another trainer that they bought after they crashed theirs. I would stay away from the fiberglass plane--they are inherently heavier, which = higher wing loading, which = even higher landing speeds, nastier stall tendencies, and so on. Plus, once you crash it, repair is much more difficult for a beginner. Sometimes when you crash your balsa trainer, you can re-build it. Once you start cracking that fiberglass, it will be difficult for a beginner to repair it. You need experience before you move to a plane like that.

Trainers can fly in the neighborhood of 55 to 60 mph. Is that not fast enough for you?