Dan,
I have both the small Magic Ball and the large Magic Ball and swear by them. To not be limited by the "drop-in" cutout of a typical head is priceless. The quality is superb. Those Germans!
But I also like the modularity of their system. You can start with a Magic Ball and then add their panorama piece and then the most amazing attachment device I have ever seen, the Q=Base. More on that in a minute...
The Magic Ball comes in three sizes, S, M and L.
I also have their panorama piece as well...it stacks on top of the Magic Ball.
And now, for the icing on the cake. The most incredible device for attaching an Arca Swiss outfitted camera to a tripod head....
It is called the Novoflex Q=Base. This is it...
So, this is how it works...
You rotate the silver base counterclockwise to prepare to cock the base. Once rotated, you press the blue buttons together to cock the system so it is ready for an Arca Swiss plate. Now for the sheer brilliance...
You literally place (drop) your camera on this base and the spring loaded receivers release to grab your plate. All ONE HANDED!! You cannot remove the camera unless you press the blue buttons together. Rotate the silver ring to fully tighten the system and ready to go.
I can't stress enough how much of a game changer this was for me. I own three of them. One on my larger Magic Ball, one on my small Magic Ball and one in my bag at all times for my small sony or just in case.
HIGHLY recommended!!