I've only had a tire fail with a single axle (a non-event, just annoying), so can't comment on that aspect. Backing is supposed to be easier with two axles, but I didn't find much difference. I did find a difference at the toll both, and when paying for replacement tires and when repacking twice as many wheel bearings and replacing twice as many brake parts.
I had experience with an earlier jayfeather model (then by another name.) It had some significant structural issues that I felt should have been covered by the structural warranty, but weren't. But I think with even a new RV you have to assume warranties won't apply for one reason or another, except for completely obvious component failures. On the other hand, overall I was pleased with the Jayco workmanship and component selection, vs. previous RVs I'd had experience with.
There's a big difference between 2009 and 2015 - more than $1000 difference, assuming similar models. Just having the roof and rest of the vehicle sitting outside for 6 years will cause remarkable deterioration of almost every part of an RV.
2000 Chevy Silverado 1500 x-cab V8 5.3L