I'd see if you can ride the larger frame, funnily enough I've been having this debate with myself only the other way with Marins, dropping a frame size and playing with stem length, but with the Marins, there is only limited impact as while the size on seat tube goes 17.5 to 19, the top tube is only 22.5 to 23. A bigger impact seems to be the change in head tube means the bars sit lower with a smaller frame so more bent over, I've been looking at Kona's for a change - do drop us a line if you do change frame