My proforms cracked one after about 1 year of use, 500lift, 350spring pressure, my buddy broke one too, and in the process one of the adjusting screws snapped and fell down on the camshaft, cracked a lifter, destroyed the lifterbore in his 340. He was running a performer rpm camshaft. I dont thrust them any more.
Look for used good ones or step up to 450 dollar and buy the ones from mancini.
He (the OP) asked for someone that has actually used them, and you have and it broke. So did your buddy. The OP did NOT want to hear this!!! He has his mind set on using them and wants somebody to say "that was a good choice, Johnny" ... LOL.
