People have told me there is flexing problem with certain year Sierra's and Sandpipers in the frame that causes cracking in the walls, around the pin box and around the slide out in the bedroom ( we don't have a slide there).
We haven't seen any damage on ours so we bought it anyway. The way the people talked on this other forum it seemed to pretty common knowledge. I do remember hearing about Sandpipers from local people.
So far we like ours and hope it lasts a long time with proper care and repairs.