I just saw this post too - so again sorry for the late response.
I've owned 2 Northlands & they were both very good & dependable. I purchased one new and took very good care of it, inspected everything anually (roof, seams, etc) and never had a problem. The other one I owned I purchased used & it was 6 or 7 years old. It too had no problems.
Like anything I think it's a matter of proper care. I have a SIL who purchased a Northland but it wasn't well taken care of & ended up with wood rot in the walls.
So if you are going used look it over well - especially roof, seams around vents, seams on siding etc.
Good luck