Mirroring hole patterns create serious issues when updating the original source hole:
Changing from one standard hole to another causes the mirrored holes to fail. There are workarounds, but it shouldn't fail.
Changing from a simple hole to a standard hole does not update the mirrored holes at all without any failures. This is very dangerous, because we've had a situation where the new standard hole visually looked the same as the simple hole. The engineer though the mirrored holes updated (since there were no error messages) and the part was almost released with the wrong holes!
Please update the mirror functionality to accommodate both of these use-case scenarios. The second one is extremely dangerous and can cause products to fail if the wrong hole is used.