That thing should do it.
But I'm not sure if that thing's able to seperate the incoming MIDI-events, looks like it's just a MIDI-merger that spits out the signal 6-fold.
So the question is, can you address any MIDI-item for itself from the Sequencer as you could do with a common MIDI-interface?
I don't think so, but if you jsut use it for solving combination problems, it looks like a good buy.
Also, most synth can be used in at least two MIDI-modes (Multimode, MIDI-mono-mode, Poly/Omni-mode, Homophonic mode, Monophonic mode, declaration may differ). Only the CV/gate and DIN-controlled synth are mostly monophonic, so it does not make a difference anyway.