First, let me say I didn't read all the posts.
This is just my opinion but a full wall slide really won't have any more issues than a regular slide. Friends of ours who had (sold the unit as they wanted to get out of RVing) didn't have any problems with their full wall slide.
I wanted four separate slides as I didn't want to duck under the slide for the bay services. Many people with full wall slides connect the electric/sewer then put their slide out which works fine for them.
I also didn't want the weight of the fridge in the slide out. Our four slide unit gives us plenty of room and I'm OK with the 'hour-glass' middle as some might say. None of our bathroom facilities move in a slide (except for the kitchen area).
A person just needs to find a plan that they feel comfortable with. I have to say that there have been a few times where a tree or some obstruction would have limited a full-wall slide. Seems like it relates more to the electric post, fence post or tree.
That big slide, I would imagine, is very heavy and would need a strong mechanism to work. For those that are looking at units with full-wall slides, just make sure the unit that you pick has a good system.
We are looking at replacing our current coach and the new coach will have four separate slides. It's just the way I want it.
Safe travels,
MM.