Just throwing my two cents in, but I've read on three or four pellet stove forums where a generator fried the main board because of a square or modified sine wave. An expensive fix, plus no telling how long it would take to get a new one in. Not exactly a position I'd want to be in during a winter power outage.
We've also just replaced our refrigerator and one freezer, both are Energy Star rated and I just didn't want to take a chance of burning up anything on those expensive items.
On a good note, I ordered the Champion from Costco on the 8th, they stated it would take from 2-3 weeks for delivery, then got an email later on that day. It's supposed to land at my doorstep sometime Monday.
I've had one of the older Champions for several years now, it has been a beauty, easy to start, not all that loud and I haven't had the first problem with it.