MRL Roller Lifter Street Durability

I don't know for sure. The one thing I know is what moped was saying.
Overkill on spring pressures or worn out springs will screw stuff up before a roller lifter fails.
As my budy Ted said, Harley used roller lifters since the 20's. I used to put a7K a year on my bike which isn't crud next to some riders I know whipping out as much mileage on there bike as many cars do @ 15K+ a year.

MRL worked with Comp Cams directly to make a better lifter. It took a while to work with them until they finalized the current lifter. Comp now sells the redesigned lifter at a heftier price.

Between a good quality spring and oil, I can not see a reason for failure.