Nice looking set up that you have there. I am 80% complete with my build, just waiting on getting the trigger and components back from getting some work done to them. I'll get some pictures up later.
It is my understanding that PMAG's and EMAG's are basically the same, just that the EMAG's have a slightly different contour for Sigs and H&K's. YMMV
As fars optics and PMAG's go, I would highly recommend
Primary Arms. They get good reviews over at AR15.com, but it seems like some one just bought their last M3 clone last month :whistling: . I was a little skeptical at first, but the thing is solid. All that is on top of the fact that I add the high-cant mount for only $10 dollars more. Their customer service was top notch from my experience and shipping was extremely fast and reasonable. YMMV
Editted to Add: Just notice the Primary does not do sales to CA on PMAGS. Not sure what that is all about...you guys and your "bullet buttons"