I have the new type (space for a guider but without the guider) GEM 45.
I could not get it to reliably connect to my Macbook until I used a powered USB hub. Since then it has worked perfectly, well almost. I found that the USB B connector on the mount was not very positive and sometimes (usually during a long slew) it would loose contact. I replaced the USB B and the power connector with a 3 pin and 2 pin locking connector.