These 4-output presets can handled with the following routing:
Again a variant of the original AD/DA routing with a different take on how to use those 4 free firewire channels. This one is 4 channels into DSP A, then sent to DSP B, and finally 4 channel back into FW1.
Note that you could go for a mixed variant, where FW1 inputs 5/6 go into DSP-A and FW1 inputs 7/8 go into DSP-B, and both DSPs have the first 4 of their outputs mixed together in Main Out block 5,6,7,8. Nothing wrong with having a couple of these routings available and switch when needed. This might even be doable with a MIDI program change message.