Well - I haven't used them and i've never had a cam failure that wasn't due to my own stupidity or an overlooked step. I stay away from high spring pressures because I build street engines. That's what will kill the cam. If I need to run a large cam, and it needs a big spring, I'd use the EDMs.
As far as do I believe they help? Yes - I'm sure they do in those special cases where extreme fast rates of lift mandate heavy springs with a flat tappet. Examples of these would be the SQ, -12 & -13, or XX Comp lobes. We're talking pretty ragged before I'd worry about using them. Imports have been using EDM holes in the valvetrains for years because they work. But that being said I'd bet the farm that the vast, vast majority of mopar cam failures has everything to do with assembly/builder/first start/oil issues rather than the camshaft design or lifters.
