We owned a 2002 Titanium for 12 years. We live in a very wet part of the world and our major issue was leaks. One, due to a leaking awning foot resulted in some of the hardwood floor being replaced under warranty but the most serious was leaking seals in the bedroom windows resulting in some delamination on both sides forward if the windows. This showed when it was around 5 years old. Although repaired, it never looked right again. That said, we had very few problems with it otherwise and it served us well.
If our new Grand Design does as well, (minus the leaks) we will be very happy with it.
If I were looking to buy another, I would look very closely for signs of leaks and have it pressure tested before buying, but I would do that with any used unit before I purchased.
The Titanium owners forum (already linked) is a great source of information and there are some excellent photo galleries posted by members showing how they have dealt with different issues.