Would there by any problems with using XTR 12 speed 2x crank 38-28 with an otherwise Ultegra di2 12 speed shifting system? Just looking for some lower climbing gears. Aside from this, not sure if anyone makes a 12 speed 46-30 now and could get the 105 11-36; also hoping that ZTTO and such will come out with maybe a 10-36 (SRAM has one but would need new freehub) since they are lighter.