MRL Roller Lifter Street Durability

I really wish I had more miles on mine so I could give some feedback on durability the MRL lifters. I bought the Pro-Plus with the larger rollers. The springs have over 200 seat and 600 open pressure. Cam is 266/272 @.050 and (was) shifting at 7200. The engine only has about 220 miles on it with 8 passes at the track, but no issues thus far with the lifters.