I can only speak for Class A Diesel Pushers. They are getting better and better all of the time. As they became heavier manufacturers ran into issues with overweight front axles etc. This has been resolved for the most part. The 2006 - 2010ish range saw a lot of other issues from Tiffin and others. These problems seem to have been fixed. They are not only made better but floor plans have greatly improved and 'all electric' Coach's are now the most popular for many good reasons. If I was looking at used I would try and stay to 2012 and newer!