Hi and welcome!
I have a 2007 Damon Challenger 355. Similar to the one you're considering; the major differences that I noticed is that mine has an additional slide for the kitchen and a different bathroom configuration.
I bought mine "new" in 2010. It was old stock that the dealer hadn't been able to sell so I got a great buy on it. Since then I've put about 56,000 miles on it and have spent many days and nights in it.
All in all, I like it! It doesn't have the fit and finish of the more expensive rigs, but I have yet to find a floor plan that I like better. Some of the hardware is pretty cheap stuff, but easily replaced. I've replaced (and upgraded) the faucets in the bathroom sink and shower and the kitchen, as examples. Also replaced a very cheap feeling bathroom sink with a cast iron one that was on clearance sale at Menard's.
The TVs were old analog CRT models that I replaced with much lighter (and better) flat panels.
Several window latches have failed and been replaced. A couple of the double-pane side windows have gotten moisture between the panes and need to be reworked, but that's about all. Not too bad, really ...
I've been very happy with the Ford F53 chassis. No problems at all. Only maintenance has been routine fluid changes and a set of tires about about 33,000 miles.
When we bought the coach, we wanted to spend conservatively since we weren't sure we would enjoy it enough to keep at it. After five years, we're still enthusiastic and haven't yet decided to upgrade to another make or model.
Get a good inspection by someone you trust who is knowledgeable before you write the check! The systems aren't rocket science, but there are lots of them, and poor maintenance can take its toll.
Coyle & Sue
Cassity (Labrador) and Rylee (Standard Poodle)
2007 Damon Challenger 355; 2003 Element toad