Very cool of you to offer a test drive, but I run a M&P not a sig..yet!
Mine is the 3.5 moa version too, my dot looks horrible compared to yours, it's not even a dot lol. I'll see if I can get a picture.
Edit: so I guess I have bad eyes? Or an astigmatism? My dot looks just like yours through my iPhone camera. Small crisp and beautiful. Real life.. Not so much.