I'm still of the opinion that line visibility can be an issue when fishing slow-moving finesse lures in ultra-clear water.
I see the A-rig as a reaction lure. Kinda like a Plopper or even a spinnerbait. It's chugging thru the water clanging and flashing and vibrating and the fish says, WTH???? Then he attacks the dadgum thing for invading his territory.
Conversely, a Ned or shaky head bite is a feeding bite. He sees it, goes over to investigate, may pause a few seconds, and then eats it. I just think there's more chance for line visibility to tip him off that something ain't right. Not that he/she has the mental capacity to know it's fishing line, but I think we all agree that fish often are reluctant to take something that isn't realistic, especially with a slow feeding bite.