Randy: Well, a Z-Wing weighs a lot less than a 15 lb. ball!
. I can only give my experience using it for trolling, so here goes. The Z-Wing puts more downward pressure on the downrigger, so it has a sharper angle downward. This lessens 'blow-back' gives you a better idea of how deep your bait is running. It also tracks a bit straighter in a turn while trolling, in my opinion.
I was usually targeting kingfish and wahoo with it, although you would would get anything else you might get on the the troll. I got my only blue marlin with a Z-Wing. I soon learned to forgo the clips that are commonly available and instead attach the fishing line by a few wraps with a #64 rubber band. This provided a much better hookup ratio, especially with hard-mouthed fish like wahoo.
You would have to be trolling at least a few mph for this downward pressure to kick in. I usually trolled about 7 mph. They do make a live bait version for trolling live baits at slower speeds, but I have not used it.
I don't know what style of fishing you do up there in Burlington, VT (Narwhal, maybe?), so can't really say if a Z-Wing would be of help.
Rob