In the last week or so I have seen sales popping up all over the place for the gen 1 Holosun sights, as it looks like they are clearing stock to make room for the V2 versions.
I have 2 507C's and 1 407C. The 507's are on my G45 and P10 (both with milled slides) and the 407 is on a Canik SFX. I've got a couple of thousand rounds on each of those and I have had zero issues. The G45 is my carry gun at work now. I am planning to swap over to a 508T V2 for work and pick up a 507K and have my G48 milled for it.