I have only been using the HK factory plates (which work very well indeed) but yes, the CHPWS plate would drop the SRO to right around RMR height.
I think you’re spot on. If you carry the SRO then it might be helpful. I don’t think it’s really necessary, though. I personally think it might be detrimental on the RMR- it’s fine at the standard height, but it would, I think, take up too much of the relatively smaller RMR window. So, perhaps the CHPWS thin aluminum plate for an SRO, but I definitely prefer the robust and well designed HK OEM plate for the RMR.