Although we don't own or sell Champions, we are a factory authorized service center for Champion. Several of our friends and customers own champions and seem to like them. In 2 years we have never had one in under warranty, so that must say something good about them. However, one friend has one that, watt rating wise, should of ran his roof air conditioner on his travel trailer but wouldn't. I honestly don't know if the watt rating is a little over stated, or if he was trying to run too many other things at the same time. That being said, i would buy one rated one step higher than what you think you need.
Also, Call Champion before purchasing and find out where the nearest service center to you is located. You don't want to buy one only to find out you have to go to Bowling Green Kentucky for warranty service! The Champion headquarters are located about an hour from me, and they have always been nice, prompt, and economical the couple times I have dealt with obtaining parts for non warranty repairs. (I think a breaker and an outlet have been all I have ever replaced on a Champion) As with any product, DO NOT lose your receipt, warranty service requires it!
Again, I don't own or sell Champion's just fix them, I am just going off feedback from our customers that do own them. Your mileage may vary.