You should look at both in person if that's a possibility. I don't like the SB personally, the dot is too close to the bead and if your gun/choke/load is off poi/poa with the bead, it's going to bother you a bit. I like the dot to be well up above the bead/rib. The 336 mount is plenty low and more secure. My SOP on a new rig is drill/tap for a 336 and bed it straight with the receiver. You can also run multiple other reflex sights on Burris mounts if you decided to stray from the FF line as well.
