I'll note that when I shoot clays, I rarely turn it on. I've tried it both on and off and really couldn't tell much of a difference. That said, it's just something I do for fun. I'm not good enough and don't do it enough to be at a point where it might have a noticeable effect one way or the other. I wouldn't purchase one for just that reason.
The biggest plus for me on the FF was that when turkey hunting I could still use the bead if needed. The line on the rear of the FF actually works very well with the bead and gives me a better reference point of alignment when turkey hunting than if the FF wasn't there and I was only using the bead. With an Indian Creek choke and turkey loads, it's more like shooting a rifle than a shotgun....and for this, the FF is a nice point of reference both off and on.
Saw a video the other day where the battery died on the RD and the guy was still able to get his bird looking through it. A number of shotguns are cut for the RDs now, which puts them in line with the bead.
I can see the front sight on my Smith 620 through the FF with the very low mount I installed. No rail or PIC mount, the FF screws directly to it.
