Also in using a grapple/bucket like in Micks picture it would seem to me the limiting factor more often than not is going to be your width, more than your actual capacity.
Again I relate it to logging. Forwarders don't carry logs sideways. If all yOu were doing was loading with it, as in your trailer/truck was right beside every tree, I could see a grapple like Mick pictured being an advantage. But if you are primarily moving the tree from somewhere like a backyard to where it's loaded, bmg all the way.
And with brush, I could feed my bandit 250xp like no tomorrow with the bmg, never to rarely having to handle any brush by hand. Drag, or heel it(like willie described) and travel backwards to the chipper and drop the butts on the tray, grab them a little longer with the grapple and jam em in.