I was fishing on bottom with this rig - Commonwealth is only 3-4 feet deep in much of it's perimeter - it's deepest is barely over 10' in the middle in the summer. It's not a deep lake by any means - which is one of the reasons it gets so weed choked. The thing with the weightless rig - carp are very finicky, and they will spit a bait before you can react quite often if they feel any weird resistance. THe weightless rig gets rid of that resistance, and the fish will mouth the bait a lot longer. I've watched them drag my corkie 8-10 feet before setting the hook just to see how long they mouth the bait before making the decision swallow or spit. Typically I set the hook as soon as I see it start to move, because I don't want them swallowing the bait, since I am almost a 100% C&R carp fisher. I might keep one for crab bait at some point - but since I don't eat carp, I don't keep them. I won't kill them just because they're carp either. They're much sportier fish than hot dog trout that brings in the crowds.
It's really funny when you hook into a hot carp, a crowd gathers to watch you battle it - and as soon as they see that golden flank and realize it's not a trout - 9 times out of 10 the crowd disperses like they were never there. Usually the only ones that stay are parents and little kids, because kids generally don't have the "oh, it's just a carp" hang up that adults do.
Why someone would rather catch and release 10 inch stockers than 7-10lb carp is beyond me, but whatever floats their boat!