I have been playing around with CrossFit Challenge #2, 21 DB Thrusters with DB's totalling half BW.
I put up 17 on Sunday with 2 60 pounders at a BW of 235. My right arm failed miserably at 18 and the DB bounced off the plyo box and back at me.
I am a month or so away from the challenge, I hope, and I think that rythm is the key. when I lose my "stroke" it all goes to crap.