I’ve fitted them,it’s no drama. The receiver ring is soft and drills very easily.
It’s a very solid mount, as low a possible and the rear locking wedge is very strong and solid. On one that I fitted I had to shim the wedge, but that was easy and just .010 shim stock.
Like you, it’s the best I’ve seen. The length of the pic rail is ideal and the strength and solidity of the unit is exactly what it should be.