The factory pads tend to dust up very quickly because of how soft they are. Due to that soft compound, they don't need to be kept warm for peak braking efficiency (which makes them an excellent street pad) but it means that they don't cope with heat quite as well.
The sports pads tend to be a bit more metallic and harder. It means that they won't go off on you if you're hammering them, but they'll wear the rotor out faster and squeal when cold (since you're not getting the same amount of braking effect).
If you want to avoid dust when commuting, get sports pads. They might squeal, but should have relatively less dust. You'll notice that hard braking on cold pads won't be as good, but if you're commuting you're not panic stopping anyway so it shouldn't be a problem.
As an aside, the Brembos on the Z33 are the same brakes as on the GT-R (not sure which series, though) which might make finding pads a little easier.