Check for structural cracking around the slide openings; friends of ours had an Allegro Bus, 3 trips back to the factory never solved the problem. A few months ago I passed one on the interstate, same crack in the same location.
As how they are made, I like the Monaco construction method better - hung wall (Monaco) vs laminated (Allegro).
With that said, I have no idea how Monaco is doing lately. They went through bankruptcy, bought by Navistar, then sold to the REV group. Pre 2008 I would have recommended them highly, today I just don't know either way, good or bad.