Well, I've gone through all the floor plans on the Coachmen website, and cannot find a 29SE in any model TT. Googled for images on a Coachmen 29SE and got pictures of Freedom Expresses, Catalinas, and Apexes. So, I don't know which camper you are buying. However, I can tell you that my Catalina 25RKS has had absolutely no problems. I have gone through it with a fine toothed comb and been unable to find anything wrong. There are plenty of mods to do, to be sure, but that's part of making any camper your own.
Though I have no data to back it up, I have come to suspect that TT's of any manufacturer are pretty much trouble free as long as they are under 28 feet long. Beyond that, I think the frames tend to be too flexible, which introduces problems.
Our old TT was 24 years old when it finally wore out, and I imagine our new one will last at least that long, as well.