I've mostly dealt with their Fusion line, owning and using most of it over several years, but have had good luck with everything of theirs and their customer service as needed. Reaction and replacement was quick when I received out of spec parts. Their ATOM line has definitely struggled as far as supply and only two shops offering the work on stock slides, so you're not wrong. Hopefully that will change, I've held off on RDS for a long time since I want to avoid direct mill and being stuck with a platform in an evolving market, and the fact the RDS themselves haven't seemed 100% yet, but I think if ATOM 2 is easy access paired with the ACRO and these new Holosun options, it may finally be time to move forward.
Speaking of Holosun, I have never considered them for anything before, but this 509T, 507K and this other unnamed low-profile option Steve Fisher posted on Facebook really has me re-thinking the brand.