I had my P07 .40 and P09 9MM milled for the RMR and back up rear sight at Primary Machine years ago. Zero issues with the work or the back up iron sights they installed.
The good thing is, milled for the RMR, you can also buy/install a Holoson 407 or 507 red/greed dot if the RMR stops working correctly or you become otherwise dissatisfied with it. Both my pistols now have Holosons on them and replacing the RMRs was no issue/problem at all.