Just received the Markins QL-48 Quick Release Clamp to upgrade my Markins M10 Ballhead. (if you want to know how I got the existing clamp off, that is another story)
I have RRS-L plates: BD300-L and BMBD200-L
I also have Markins Camera Plates: P300U and P200U
The QL-48 initially fit perfectly (as expected) with the Markins plates. Tight, so that they couldn't be moved thru the clamp, but not so tight that the lever closing effort seemed excessive.
The RRS-L plates, with the factory clamp setting, were much more snug. The lever closing effort seemed excessive, but still could be closed completely. I easily adjusted the clamp by turning the adjusting screw about a half turn and that adjusted it nicely to the RRS plates.
Hope this helps anyone considering this clamp. It's made extremely well as you would expect with any Markins product, I don't have a RRS clamp, so no way to compare.