Having owned a Whirlpool Cabrio with the impeller about 7 yrs ago and now a Maytag MWVC415EW like in the video Martin posted, I really like the Maytag better than the Cabrio.
With the Cabrio I was very careful to load around the tub, leaving the center open as much as possible. But I always had problems with towels and levi's going out of balance. The machine would attempt to balance by re filling for the rinse, and if I didn't babysit it it would fill over and over, never balancing itself. I had loaded everything in a balanced way, but for some reason these loads were always a problem.
Now the Maytag, with the agipeller has never gone out of balance, except once when I washed the Rubbermaid tub mat with the cotton shower curtain, and cotton woven bathmat. I knew this probably go out of balance because of the rubber mat so I sayed close for the spin cycles. I just pressed pause, opened the lid, redistributed the load and all was well. We have a set of bath towel from Pottery Barn that were a gift. The are so heavy, they are like rugs. In my LG FL, even using low spin speed it took 2 hrs. to wash these because each of the 3 spins took at least 15 mins just to decide that it would spin.
The Maytag washs these towels, and rinses them beautifully on the Deep Water Cycle, heavy soil, hot water in 55 mins. and never goes out of balance. So my experince is that the agipeller does help some loads to keep themselves around the tub, instead of moving to the center. And I agree with Martin that it probably does encourage people to load properly.
Sorry to ramble on, but I really do like this machine. Its a real set and forget kind of machine, which is what an automatic washer should be. I don't feel like I need to keep an eye on what its doing cause it just does what it supposed to do and does it well.
Eddie