At Lv75, if I WS'd Khimmy 4 or 5 times on SAM (Approx. 4800-6000dmg), I don't think a RDM could catch up unless he was tanking. On that same note, if I was tanking Khimmy on SAM, there's no RDM in the world who could have caught up...and it's not like I was Amano'ing it or anything.