Have 63s and I couldnt be happier with them. They ride awesome on the street (even with the dual shackle) and flex tremendously on the trail. If you are planning on bobbing your frame or bed though I can see how the shackle would then stick out too much and get you hung up on stuff. If that is your plan then I would say go with the marlins, ive heard nothing but good things about them. Thats what Im going to be running up front eventualy, but i plan on keeping my rear end how it is.