I read up on them a while ago. As long as they are a bleed down lifter, they will continue to bleed down through the whole lobe cycle, regardless of how you set them with a feeler gauge. Maybe not as much as at low RPM, maybe not as bad as the older design, but they will still do it and I doubt they would reach absolute "zero" bleed down.
It's a function of the lifter, it's built into the design.
It's like bailing water with a bucket that has a hole in it. The faster you bail, the less water you will lose through the hole, but you will still lose water.
Oil temp, viscosity, pressure , aeration and valve spring pressure are all factors that also effect the bleed down rate.
Having said that, it doesn't mean that they wouldn't be of some benefit in some applications and I have read where people have had good results with the newer lifter.