The S6 has a threaded feedneck if i am not mistaken, so no cram and jam for it but you can do the stick feed in the feedneck method. The moving backblock isnt an issue unless you remove the beavertail. It will keep it from ever hitting your mask.
Both can be equipped with the same pump handles. It all boils down to which one you think looks best and will fit you best. I personally, like the S6.5 the best. Aside from my first CCM, my SS25 i bought with bonds my grandparents gave me growing up, i have kept my S6.5 over the other 7 CCM markers i have owned.
There really is no wrong choice between the 2 IMO.
Last edited by crazyorigin; 12-01-2012 at 10:24 PM.