Larry N. said:
I've now had two rigs with full wall slides, and both have been excellent in that regard. Note that the designation FULL wall slide differentiates it from slides which are not nearly the FULL length of the rig. Both of my rigs have had the slide from just behind the driver's seat to the back end of (whole wall of) the bedroom in the rear, leaving only a small section of front and a small section of the rear of the rig that is not part of the slide.
They have indeed done a good enough job. Since a slide is normally either fully open or fully closed, the manufacturers have generally engineered them to be more than adequately strong in both conditions. A smaller slide would, if there were a structural problem with slides, have the same problem as the full wall slide, but just over less of the coach.