I used one all last season. Never did get a shot, but that had nothing to do with what I was sitting on. I find I can sit much quieter on one than anything else I've tried. I try to pick a tree big enough to break up my outline. Sure seems to work.
Not trad, but opening day of gun season I hunted with my son in a shotgun only zone. Had a doe walk up to within about 25 yards of me. Couldn't get twisted around enough for a shot. Then she walked into some brush and came back out within about 5 yards of my facing straight toward me. She never did figure out what I was - turned 180 degrees and left me no shot except straight up her butt. I passed on that one.