On.
When I hit my target, I don't notice them. When I miss, I do notice them, and correct based on where they're going.
I find them more accurate than my gunsight, which I also ignore for the most part. The gunsight is really only an accurate representation of where your bullets go if you're flying level and at 1G. Any deviation from that and you can toss the gunsight out the window. I seldom fire while flying straight and level, so the gunsight is seldom "accurate" for me.
Personally, the more attention I pay to the sight the worse I shoot.
On the other hand, the tracers always fly in the same area as the rest of my bullets, so give me a fairly accurate representation of where my bullets are going no matter what my flight attitude is...