I've had some "issues" with my 22014 Itasca Spirit 31K. The skylight leaked early on and was resealed 2 or 3 times, but still leaked. We had to take it off, remove all caulking on the roof and skylight, resealed it, and it hasn't leaked since.
When it came from the factory the waste valves were less than 6" above the ground and a considerable distance behind the rear axle. My son replumbed both tanks and gained about 4" ground clearance, and also changed from two separate valves to a Y fitting with both valves, as well as moving it closer to the rear axle.
I also had a problem with the floor sagging between the frame rails in the main living area by the sink. They had no lateral support under the floor, in about a 6' section, as well as a shorter section forward of that. That was corrected by Itasca allowing me to take it to a local metal fabrication shop where they installed a total of 4 cross braces on the frame rails to add support under those spans.
I also developed a leak in the cabover. Everywhere a leak could develop was resealed, but the leak still persisted. It was eventually discovered that the seam running from side to side where the front cabover wall meets my vinyl
roof was never properly sealed. It looked fine but never really stuck to the fiberglass of the front wall. That was all removed and properly resealed and hasn't leaked since.
My MH is kind of an oddball in that it is a 2014, although it was built in Jan 2013. Sometime after building mine they went back to the fiberglass roofs which they normally use. They also had corrected the issue of the low hanging dump valves in a later model I saw. I can only assume they have corrected the sagging floor issue, since when I contacted them, they admitted it was a known issue.
Overall we're still quite satisfied with the MH, and realize it's a lower end unit, which meets our needs and expectations. It handles fine, without any of the issues that many seem to have with the longer E450s, it's not too bad on gas. The only thing that bothers me, is that at 32 1/2' long, there are a number of places I can go in my 24'er that I just can't go in this one. That's just the price you pay for having so much more room.