@Matt
We have tested with Cura but you have to change a few variables in the firmware. Basically in slic3r you can adjust the acceleration so it overrides the firmware and in Cura you can't. I hope to upload the new firmware tonight.
#edit: we already uploaded the new 1.5 firmware we just need to upload the 1.5 XT firmware. Please note if you have gMax 1.0 the wiring has changed for the hotends and blower fan. Refer to the wiring diagram in the manual.
We changed these settings in the "configuration.h" file:
#define DEFAULT_MAX_ACCELERATION {900,900,100,1000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.
#define DEFAULT_ACCELERATION 900 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 900 // X, Y, Z and E max