The Jay Flight is a good camper. We do service them, but mostly for appliances which is something we do for all manufacturers.
New or used either way the standard stuff applies. Make sure there are no leaks from above, make sure all appliances are in good working order (don't rely on the punch list), and remember you do not have to purchase the extended warranty from the place you purchase the RV from.
As an aside you will probably get more from selling the pop up than you will on a trade in. Pop ups are selling like hotcakes for us right now.