With our 5er, the slide room carpet had a flap out past the slide room floor that was to hide the gap with the white plastic round down when the slide was out. The flap was not tucked in under. It went out a little onto the main floor with the slide out all the way.
The whole slide floor underneath went in and out without touching the main floor it seemed--but somehow it scratched it in a couple of spots. The slide had no rollers under there. Once out the slide floor dropped down to be level with the main floor. Coming in it had to first climb up the round down and then be higher than the main floor
With a strip of carpet at the edge of the main floor a few inches wide (the Komfort guy said make it at least 4 inches) the slide room carpet flap was now on top of that main floor carpet strip instead of vinyl. That was said to be enough to stop the scratching of the vinyl part.
Many floor plans I have seen keep a strip of carpet along there, but I think that is more for comfort where your feet go when sitting on the couch in the slide room. Your feet seem to go right on the edge where the flap is and the strip of carpet on the main floor under the flap evens it all up so your feet are not on a sort of bump. I can't say if that strip of carpet also acts to prevent scratching the rest of the bare floor with no carpeting when the slide comes in and out.
My cure without having the strip of carpet along the main floor edge was to use a mat. The mat also helped for the feet on the gap issue when sitting on the couch, when the mat was tucked in under the flap.
I wanted to put in nice wooden flooring, but it would have been too high and get ruined by the slide scratching it. the OEM floor plan had carpeting on the main floor except over by the door and in the kitchen, but the slide didn't go where the tile was. My tile job got scratched, but it wasn't too bad and when shiny waxed, you could hardly see the scratches.