I have had a couple sets of Comp's edm lifters and never had an issue,but the last several solid lifters I have used have been regular flat tappets. I have been running several different agressive grinds with high spring pressures and regular flat tappets with no issues.
I do have an original set of Schubeck lifters that I use for cam testing on the dyno so I don't need to break in lifters each time.
The last flat tappet grind I had in my 440 mule had Comp's MM lobes and regular flat tappets. At least 150 dyno pulls later it looks as good as you could ask. Good oil and the right spring pressures is all it takes.
Keith