Hi Tonytony,
surely you can control SOME parameters of the SX700 using this MIDI controller.
The (M-AUDIO Evolution) "UC33" does NOT support User defined SysEx. But many functions/parameters of the SX700 use SysEx messages. The Faders fo the UC33 are not motorized, and the Rotary knobs are no "endless" Encoders (but only standard Potentiometers).
So I think the actual benefits of using the UC33 with the SX700 will be relatively small.
P.S.
If you have an iPad: You can use an app like "MIDI Designer Pro" to make your own virtual MIDI controller.
Best regards,
Chris