So I had this idea and made a simple device to use my QDs to hook up a pump and run a whirlpool:
Now, it does work. It actually works pretty darn well, BUT, it needs some modification.
1) getting the flow started up over the side is a pain. If you can move your hose full of fluid over to the QD and get it on, it may start more easily, but I find myself often pulling off the return hose and sucking to get it started. I don't see a way around this without going through the wall of the keggle, which I may do anyway, with two new weldless ball valve setups and curved returns on the inside.
2) don't disconnect with the draw and return tubes still in your wort. Just don't. If you do, it will take you approximately 8 seconds to realize the amount of wort draining out into your catch bucket is more than the tubes could hold, which will lead you quickly to the understanding that you have created a siphon. This will cause you to panic and make a mess. Twice. On consecutive brews. Because you are sometimes not very smart. Lift it out so it clears the wort, or take it off and set it aside.
I think you could correct #2 by just shortening the tubes on the outside enough so that they would always be above wort level, or fashioning a hanger for this so you just made them sticking horizontal.
But, in case anyone was interested, this does work really well once you get the whirlpool started. It's better than drawing off the ball valve, because as hops and trub drop out and down they go right into the ball valve tube and are returned (usually near the top) to drop back down again. I ran through my chiller and returned while using my other pump on this whirlpool tubing and ended up not creating much of a trub cone at all.