I'm not sure if trackpads have the same ergonomic properties as a trackball. It's possible but I might wait and see if any research or anecdotal evidence emerges
It's worth noting that the Apple trackpad is not only way bigger than a laptop's touchpad, it's also angled so you're not resting your hand on its edge. Also, if you've never used an Apple touchpad on a recent Macbook/Pro (the ones that are glass instead of plastic), you'll probably be surprised at how good the accuracy/tracking. They're much better quality than the Synaptics touchpads that are common in PCs.
My other preferred device is a thumb-ball trackball. I have a logitech trackman, and the discontinued one from Microsoft. I find those much more comfortable, if a bit problematic for high precision. I just wish I could get a bluetooth one.
The ball's diameter allows pinpoint accuracy when needed, the weight allows a flick with momentum to carry the cursor across two 30" screens, the scroll wheel is under your ring finger for simultaneous use.
That said, the recent magic trackpad is growing on me.