It's real easy to tell looking at the slide from the outside. Some of FR campers are lower to the ground so the wheel well extends above the floor surface. They hide the one side usually under the dinette and the other side under the couch which then requires that style of slide.
If I was able to change out the sofa in our Rockwood 2605 TT with recliners, I would have probably kept it longer. Unfortunately that's the negative of that stye of slideout.
Nights camped in 2013 - 55, 2014 - 105, 2015 - 63