Hi Jen,
I'm not an expert on these things, but I do have the dual axis drive for the EQ-3 mount. I quickly found that it is a bit of a pain! You can't slew the scope any faster than 8 times tracking speed, which is sloooow! I now find that it is easier to just fit the RA drive for tracking and use the manual control for the declination axis. The RA drive tracks very accurately but the hand paddle only really allows you to move, very slowly, to center objects, and to scan around the surface of the moon.
In short, I could have saved money by buying just the single axis drive, maybe you could save some as well.
And now that I have a 12" dob, I'm not using the EQ-3 very much at all!
Cheers
Chris