I had 2 at one point. I was a consumer beta tester for Champion when they were first introduced to the market, but that was some time ago.
They had some minor issues in the very early models (throttle hunting) but I'm confident that's history - my later model second unit never suffered from it.
Great units. Only complaint was that they couldn't equal the surge output of an EU200i (Honda). My eu2000 could fire off the roof AC unit on my trailer, but one single Champ 2000 couldn't do it reliably, kinking off into overload about 50% of the time after the compressor cycled back on. It was a real crapshoot. When I upgraded to 2 of them with the parallel kit it wasn't an issue anymore obviously, but that's a bigger cost and space commitment vs a single eu2000i in the end.
So, really depends on what you're going to be using it for - heavy surge loads, or not?
Other than that, great units. Again, not *quite* as quiet as a eu2000i, but a hell of a lot cheaper, and track day vs campground (where noise is more of a concern with a campground) I can't imagine that'll be an issue.