Timing Pulley 40 D.P. Vs MXL

Dose one have any advantage over the other. I am some what a beginner with timing pulleys and belts.
I see that the 40 DP has a pitch of .0816 and the MXL has a pitch of .080 Is their any reason to use one over
the other.

I want to set up a 10 turn potentometer with a pulley and turn it with a small gear motor box. I was planning to
use one of the Tamiya gear boxes. I am going to read and control the setup with a basic stamp and A to D IC.
Its just a test setup to expierment with.

Any suggestions on which pitch to use. The 40 D.P. or the MXL. Or dose it really matter?

The project is for a Ham Satellite tracker like the one shown here sites.google.com/site/marklhammond/saebrtrack

I want to build a small test setup with Tamiya gear motor boxes to expierment.