anyone using diopter sights on their ar?

[YVK]

I suggest that you try and demo before you buy them. There is more to irons/optics interplay than co-witness alone. I am not 100% happy how these interact with Eotech XPS; I assume that 511 and XPS are similar in height and window size. That's why I bought ADM riser, but that puts Eo just a bit too high. Currently I am using this optic setup with Centurions, but I actually plan on moving Eotech/riser to my AR with standard sights in future. If demoing it not possible, maybe you should contact Monty and see what's his return policy; he has been an absolute professional to deal with.

[HeavyDuty]

What was it that you didn't like about the XPS without riser and the diopters?

The chances of getting hands-on experience with these prior to purchase are pretty slim. My (admittedly limited) experience with HKs makes the diopter appealing.

[YVK]

I thought that front sight obstructed too much of Eo's window. I admit that I am a new Eo user and haven't compared how it looks on other ARs with fixed front sights. I am also not anal enough to measure if absolute cowitness Aimpoint mount raises AP a bit higher than rail-mounted Eotech, but I didn't get that perception of obstructed view with an absolute cowitness-mounted Aimpoint. So this is 100% subjective.
Again, talk to Monty; most vendors let you return their stuff if you're not satisfied, especially that in this situation you won't even need to use the sights, other than carefully mounting them on your rifle, to figure your question out.