I am reminded of an article by the late & great Pat Rogers in SWAT Magazine. He argued (persuasively) that carbine dots were sufficiently mature that the irons were no longer necessary, and that if the dot went down, the best backup would be a green laser.
Without having the substantial background of the membership here, I tend to concur with that article. When the What Would Stoner Do (WWSD) projects occurred in 2017 & 2020, iron sights were intentionally deleted. The argument was that they were unnecessary anyway, and that removing the BUIS opened up more rail space for IR/NV and other electro-optics or other add-ons.
There may also be merit in considering exactly what sort of optics match with exactly what sort of back-ups. Without a QD mount, folding BUIS seem contra-indicated on a scoped gun. I handled a dot-equipped 10.3" AR at a class last weekend that had the dot on a 1.93" mount, and a fixed front sight. There was a hole in the mount that could be used as a sight. I'm waiting on getting a 16" PCC built, and I have the JP offset irons on it, mounted at 45 degrees, with a TLR-2AG ahead of the irons. I know that I'll have to shoot hard leans, and I'm curious to see how this whole thing will act. I will note that the JP offset irons seem a good bit heavier, and are bulkier, than any reasonable RDS.
When I first decided to get into pistol dots, I thought that I wanted the irons to absolute co-witness with the dot, and now I have a tritium standard high front for like a "lower-1/10th" co-witness. I just loved the screen and the visibility, and I'm satisfied with the durability and battery life of the existing options. I do have a TLR-8AG on the pistols, and there was a class last fall that was some weird and awkward position, and rather than trying to get behind the glass, I just hit the light/laser, and went that way. If the dot goes down, I'll do the same.
Of course, this entire plan does become very battery dependent.