No change is required to the surface SDK as far as X3 is concerned.
The SDK does need updating however for some of the newer interfaces added when we did VS-700 support. We will update it sometime soon.

Noel,
 
I may be asking the question poorly and I may have missed something obvious but the big question I have is this.
 
are sends 2,3,4,etc available for controller assignments via the SDK?  The reason I am asking is that I have never seen a controller that allows for more than a single send to be controlled via a standard channel.  I am trying to determine if this is a system limitation or just something developers have ignored.

bump

Sends are enumerated by the surface so I don't see any reason why there should be any limitation there.
The limitations probably have to do with real estate.