The difference between buying new or used depends on how much you want to spend and if you're handy at repairs. All rv's will need some work. It takes a little time to get the bugs out of a new one but that's under warranty. Typically used ones will have the "new build" items taken care of, then it's a matter of how it was used and general maintenance performed. I believe a pre-owned that was used often and stored out of the elements could be a good choice.

Sorry I don't have any experience with the Montana but it seems I hear mostly good reports.

Hope that helps.

And welcome to the forum.