Yes, welcome. I have no experience with Jayco, and am not familiar with the Mountaineer 344RET, but we have an '05 298RLS and are very happy with it. There is a possibility for problems with any brand you buy, and ours was no exception. But all of our issues were minor, and were taken care of to our satisfaction by the dealer, which leads me to believe that picking the dealer is equally as important as picking the brand. I wouldn't hesitate to recommend a Mountaineer.
2005 Mountaineer 298RLS & 2003 Chevrolet Silverado Crew Cab 2500HD Duramax/Allison