I have them on two 75s and an AII.
With respect to vertical adjustment, JCS is correct - less flexibility to tinker if tinkering is needed. They also might not be compatible with great big objectives, especially with big fat barrels.
However for left/right adjustment, the instructions invite us to start with the mount in the middle of the front rail. Moving 1mm forward from there shifts the POI about 1"/100yds right. Rearwards, the same to the left.
This is in contrast to the instruction for fitting the separate-base mounts, for which the back of the forward mount should be flush with the front of the receiever opening.