I just picked up three B40-8/W's from a friend in a trade. He is upgrading to Atlas units, which offer FAR better detailing, hands-down.
However, they are incredibly smooth running units. They are perfect "club runners", I've got no problem runnning them around the club layout, whereas my Atlas units make me nervous when they are out of my reach!
The GP9's are the old Cox-brand shells, and are quite crude and ugly. But they do run nice...
I will definitely pick up some more B40's if I get the chance.