Stevie in a close one. I think his clear edge with in-fighting betters any edge Casamayor might have with movement and handspeed. I think this will predominantly be a scrap, not a boxing match.
Stevie by clear UD. 135 was never Casa's best weight. He saw his best days at 130. Stevie was quicker, and would beat Joel to the punch most the night and outbox/outwork Casa.
Casamayor did NOT have better movement, or handspeed than Stevie. I think Casamayor's ONLY edge over Stevie is power. Johnston was faster, more active, better stamina, better defense, better skills.