Three hole is preferred for mount stability. Drilling the holes is tricky but doable. I found it easier after drilling one helmet to just trade off and get a factory drilled WARCOM (standard 3 hole pattern) helmet from either TNVC or Ownthenight.com. This is particularly true for duty application.
I have used the USGI NORTOS shroud, the Ops Core VAS shroud and am currently using the Wilcox system which I prefer as it carries the PVS-14 lower and closer to the helmet when flipped up.
If you need or want to stay with USGI compatible, the VAS shroud is the slickest way to go.