I have read about the cracked frames and in all reality there are very few vs what is out there. They do have a fix on their website for the problem units. Most are the ultra lites and trying to make campers for the 1/2 ton pickup market. I am not in that class of 5er.
Looking at my frame it is the same as the big toy haulers so I am not really worried.
I also spent a lot of time worrying about it as well and then decided I would just add gussets and bars myself and get to camping.
On Lippert's behalf I would say that they do not know what people really do to their trailers and probably get attacked in an unreasonable fashion and that brings on the attitude that gets them denied service.
I am still liking the Solera toppers and I bet they are less expensive than the Dometic slide toppers.