I have an STI 4.0 Tac with the optic cut (I think it’s called the DPO cut?!?) I equipped it with a SRO. Back when I purchased it, I could only find iron sights that were tall enough for use with the RMR. These irons only sat about 1/2 a mm over the SRO. I test fit a DPP and had the same results.

I haven’t done any recent research, but are taller sights available now? I hope that with the release of the RMR HD, more options will become available.