2015 Heartland Gateway 3650BH

We have no problems except for a few minor things, mostly cosmetic, that were taken care of by our dealer shortly after our first trip. Like others have said check out the Heartland Owners site. We are always ready to answer questions. If you end up with one consider joining the owners group. There are alot of owners rallies, a great place to meet like minded people.
Oh we have a 2013 Sundance.

Have you tried looking on the http://heartlandowners.org/content.php website? Haven't been there for awhile but it used to be fairly outspoken by current owners, no censorship.

I don't have that model, but I am very pleased with my Heartland Sundance XLT. So far I have no QC issues of any sort, and the materials seem to be high quality. If you haven't already done so, you might visit the Heartland owners forum and ask there as well.