I'm a big fan of wireless keyboards, in large part because my desk is glass, so cables are a little unsightly. I have two Macs, one with the current wireless (no keypad) and one with the old A1016 Bluetooth keyboard that has the numeric. I use primarily magic mouse with both, plus I have a magic trackpad on the one with the newer keyboard.
The real benefit of the new keyboard is that your mouse is that much closer to your hand. It doesn't seem like it would be a big deal, but I really do like that. It's the difference between pivoting my forearm to get to the mouse, vs. moving my whole arm.
Of course the drawback is if you do much ten-key work - keying in a long number, such as a credit card, telephone, SSN, etc. I don't do it enough that it's a real bother with the small keyboard, but if you regularly take credit card orders over the phone or something like that, you will REALLY want a numeric keypad.