It's the batteries that wear out. A speed controller will occasionally burn up, but if you size them right that's pretty rare. But in a nose in crash, a brushless motor isn't going to fare well. I had a .40 glow engine that I drilled straight into asphalt that still ran like a dream afterwards. No electric is going to do that.

I see some confusion in the thread though that I'd like the OP to clear up. Is he comparing a cheap electric park flyer to a standard .40 size glow trainer, or is he comparing powering the standard trainer with either electric or glow? If it's the former, the conversation becomes more about the which plane flies better (the bigger one hands down) more than which power system is better. If it's the latter, then it comes down to cost vs. convenience and the number of flights he can get in in a day. 3 batteries (if he buys good ones) will be enough for a day's worth of flying. Most quality batteries will charge at 2C, so if he puts the first on on the charger right after flying it will be ready by the time he's done with the third one. He'll have a wait a little while after his 4th flight, but taking a break isn't a bad idea when training anyway.