It isn't clear what your application is, but my use for the RS2E is in furniture making, primarily with hardwood, with the occasional plywood work. In 2008 I also refinished an old lectern made of painted walnut veneer plywood where I chose to sand off the old finish before doing stain and varnish work on it.
For hardwood I think it might be faster to flatten an area with the RS2E than the Rotex unless you are really good with the Rotex. Fixing Rotex gouges would take a long time with the RS2E but the RS2E is much slower than the Rotex. The RS2E will leave a flatter surface with coarse abrasives than will the Rotex unless you are very good with the Rotex. I have 50 grit Rubin abrasive, but may never have used it on a project. The RS2E was quite effective in a practice piece with Rubin 50 grit leaving a dead flat but rough finish.
For the plywood lectern refinishing there was the constant issue of not wanting to sand through the hardwood veneer. Most of the heavy work was done with the ETS150/3 and the final work with the RS2E. The results were excellent.
My work is apparently more towards a finer finish than that some of the other respondents. These are the RS2E abrasives that I have:
Rubin: 50, 80, 100, 120
Brilliant-2: 120, 150, 180, 240, 320, 400
For work on walnut, cherry and mahogany, I usually start at 150 or 180 and then go up through 320. Sheets of these abrasives are put in a row and used sequentially with dust extraction through the CT22 with boom. Switching abrasives is fast and frequently I clean them with a gum rubber bar with the sander running just before removing them. Running through 180, 240, 340 is quick and provides a dead-flat and smooth finish. These three are my most used abrasives with 180 doing the bulk of the work but 320 being replaced the most because it wears out a bit faster than the coarser papers.
Gary