I have both, a Champion 3500/4000 and a Yamaha 2400is and yes, last Fall the stator went bad on my Yamaha and had to be repaired. Took two weeks during the heart of archery season and yes, my Champion was my back up generator! lol
It served the purpose well but I was really glad to get the Yamaha back. The constant noise of the champion, even with a very small load, got really old. The Yamaha just idles with that same load.
For the money, the Champion open frame genny is pretty good, but not in the same league as an inverter style.