Hi Steve -- I imagine this is as much a matter of personal preference (and skill) as actual performance. IME, the Magic Mouse is just about the worst pointer to use with Aperture. The Apple touch-pads are (again, just my opinion) excellent. I don't hesitate to recommend that you try one out. There are some touch-pad techniques that may not be obvious: roll your fingertip for minute changes; use one index finger to click, and the other to drag; etc.
I also recommend any high-resolution mouse (generally sold as a "gaming mouse"). I used a Razer Naga until it wasn't updated to work with 10.8; I switched to Logitech's G600 12-button mouse. The programmable buttons accelerate my work, but (imho) high-resolution is the feature you really want. I have my entire dual-monitor workspace mapped to an area about 2" x 4", and can move the mouse curser very close to pixel by pixel.
Both the high-res mouse and the touch-pad are _more_ precise than the Wacom Intuos Medium. In my hands, the cursor regularly moves a pixel or three when I lift the pen. With the touch-pad or the high-res mouse I can work at Image resolutions smaller than 100%. With the Intuos, I am better off at 100%.