(hello everybody, long time lurker here)
Developed my first three rolls with the Rollei kit and wanted to report an interesting finding. Stabilizer concentration, as reported on the bottle of the 5L kit is not the same as the PDF. In fact, it's half of that. If you use the PDF concentration you'll run out of stabilizer before time.
From my experience, the correct concentration is that of the bottle. On the first roll I had the stab with a 10% concentration (as per PDF instructions) and a few stains, then I diluted it to 5% (as the bottle requires) and most of the marks are gone from the two subsequent rolls. Hope this can help someone.