I picked up a Holosun HS507C X2 for my M&P 10mm 2.0 the other day, and installed it this morning. Installation was simple and took about 15 min. (I did cheat a little and viewed a couple of "how to" videos on YouTube!). I like the default Circle & Dot reticle, and I kept the other default settings as well. I haven't been to the range yet, but viewing some "targets" through the red dot while dry firing, the 507C appears to be spot on with the iron sights- so hopefully adjustments will be minimal when I do get to the range.