Here are features not included in the original Servo Controller:

4 extremely high speed encoder inputs
Above feature allows use of the new "Cascade" telescope encoder mode.
Industrial Terminal Blocks
Double the motor amperage
Built In Autoguider
USB AND RS232
Better Custom Enclosure
Overtravel Limit Switch Inputs
PEC Limit Switch Inputs
Homing Switch Inputs
4 times more memory for future enhancements
4 times the clock speed
Led's to show handpad status and Communication Status

All features of the original controller are included.
All exisiting SiTechExe and ScopeII software will work with the new controller.

More about the cascade controller mode:
You must use High Resolution encoders, about 13 million ticks per rev. These are available at Renishaw, and other encoder manufacturers.
The servo motors are controlled in such a way that they are moved until there is ZERO error for the Telescope Axis Hi Rez encoders.

Mount models in the low arc seconds are possible using SiTechExe with the built in PointXP by Dave Rowe. Long exposure unguided imaging is possible....