I too selected the AcraTech for a number of reasons. Light weight, able to carry up to 25 lbs, although what I use never exceeds 4 lbs. The specific capability that drew my attention was the ability to mount it upside down, such that the rotating base is above the ball, thus it becomes a panning head. It can also be used as a gimbal and as a leveling base for my nodal ninja.
The added benefit with the open ball head design, is that dirt can never gum up the ball head works, and is not able to accumulate. It is a beautifully crafted machined piece of metal.
I use fairly large lenses 12-24, 16-45 and the 55-300, either directly on the head (with an L bracket on my K20) or mounted on the nodal ninja. It provides a solid base that functions great. My other two lenses that I use are relatively light, with 10-17 or 31, its like there is really nothing mounted.
It is slightly more, but you will never buy another head - ..... unless you acquire a 32 pound K1200mm f8 monster lens.....