Weight can always be a problem, especially on a GEM. If you've got a dovetail plate on top of the OTA you can install some weights to get better balance.
If you're really serious about imaging, I would make sure the focuser can be computer controlled (for obvious reasons). In relation to the motor, ensure it is a stepper. Servos and low voltage motors don't provide enough accuracy. When I order the JMI with their motofocus, I quickly guttered it and order a Robofocus. Now I get 0.0005" steps which is nice and tight. Not to mention the Robofocus has temperature compensation. Nice feature. I wouldn't rush the decision as a good focuser can save you a lot of time. More time to gather photons.
