I tried searching but didn't turn much. I am aware that the "majority" opinion seems to be that backup sights are not really required for a competition gun but are a "must" for EDC. I've been trying something with a Glock 19 MOS with a Trijicon SRO. The 19 has the factory sights. I have shot some turning the SRO off and indexing the front sight in the center (left./right) of the bottom of the optic window, just getting the front dot to show in the bottom center of the windoww. I can group 6 shots into a 4 to 5 inch pattern Even with the SRO I'm a below average shooter. Obviously the shots are high. But I'm wondering about a taller front sight that would index so that POA would be correct. My thinking is that a RDS (probably Holosun) would be easier to mill on an HK P-30 if it could use the rear dovetail as part of the milled area.

Anyone with experience using this technique? ... no rear sight and using the front sight indexed in the bottom center of the RDS window?

Not exactly your question. But I have tried a number of times shooting using just the window of the RMR to aim the shot. Better than random fire by a lot, but nothing like using irons that are visible when you don't have the dot (also tested a bunch). Just have your P30 milled by someone competent (L&M is who I suggest) and you can retain the rear dovetail and have suppressor height sights mounted and be happy. There is no advantage of milling out the dovetail.
Have fun.

Some red dots have backup rear sights built into them. So even if you mill out the rear sight dovetail area on your P30, you could still have a backup rear sight.



Another potential option, depending on the layout of the P30's slide, is to have an alternate rear sight dovetail milled in front of the optic cutout.

There is no need for either of those options on a P30. Numerous people (again L&M is your go to) will mill one with the rear dovetail intact. And based on my experience (the m17 maybe excepted with the Bobro sight plate for the RMR) both of those options are less useful.