Definitely not a precision sight. For close up work where you can put the combination of dot and circle on a body, while both eyes are open , yes. Somewhere, around here I have an Aerotek(?) set similar to the others posted for a Glock. I played with them a little, but I found the combined lset obscured too much of the target unless the target was really big and close. It's a lot of sight in the way of your sight picture. It's not like a ghost ring sight on a long gun where the rear is close to your eyes and it "ghosts" effectively disappearing and you can still see the target through the sight. I love ghost rings and aperature sights on shotguns and rifles. This is just my experience with the version I played with. I like being able to take a longer range precision shot, if I so choose. Maybe, the SIG version is better, But, if you try them, try taking a head shot at a littel distance. YMMV
As others have said, front sight is the key. I'll put white appliance touch-up on mine and if I have some sort of color on the rear, I'll marker them out, so that the front stands out, Even tritium rears. Which by the way still glows through the marker, but subdued. In daylight, looks black.