I just mounted a Swampfox on a sumtoy RMR mount. It sits way lower than what a P-rail and mount would sit. I didn't even complete a full mounting with a P-rail as I could see it was going to sit much higher than I wanted. The only "con" for me is having the dot sitting just over the bead so I colored the bead to hide it. Not sure if that would have happen with a taller mounting. Not much of a con...