Yes, Switching between 50% spd 50% crit rate and f.DMG build isn't that hard because of the same item set build. You only need to re-allocate the point and ta-da, 50% SPD and 50% crit rate (its actually 54.31% crit rate if you include the 5% from envoy path for primary weapon crit rate). Yes, the 50% aspd bonus from your 50% spd stacks with Lion's Roar 50% aspd bonus buff, that makes your autoattack hit with a 100% aspd bonus. Again, I will explain this in a future update, meanwhile this is the only thing I could offer at the moment.