I read the first five pages before I got bored with it. Some questions were answered, some were not. The OPs unit was 6-7 yrs old. It was way beyond warranty. The OP claimed it was maintained, but never elaborated on how. The thing that bothered me most was he claimed to be "turned back". My experence is Northwood has always been willing to make repairs and when they do, it looks like new, no sign of "repair" and their prices are much less than most RV repair shops. They can even replicate the decals on an older model.
That said, not everyone will be happy, no matter what you do. Likewise every manufacturer will drop the ball from time to time.
I have seen some problems on older AFs, and as these problems came to light corrections were made on new production. Some years ago they had a lot of water intrusion problems on the front ends of their TCs (I have seen a few and it is ugly) but I believe they have corrected the problem that causes it. Maintenance is paramount, I have never had an RV that didn't eventually leak if they weren't maintained.
I helped a friend recently repair a Lance that wasn't properly cared for, no fault of Lance's - just poor maintence. As end users we hate to bear the expense of large repairs but it is encumbent on us all to do our due dilligence and learn what we need to do to keep our units in good shape and try to avoid major repairs