I can tell you from my own experience, using 2 motors to drive your gantry is not the best way. I had many headaches trying to do this on my build. A mechanical connection of the two leadscrews is a better way to go! it may be more complicated and a little more costly but the end result is much better.
Do you need the space under your gantry to be open? Is your machine wide? Can you use one leadscrew under the table? Tell us more about your design, size etc...
Checkout my build...and my problems with running two motors