Hi,
Notion only supports 4 MIDI instruments for now. Works, but I love to work with both VST's loaded in Studio One and some outboard gear. The outboard gear is connected via USB. With only 4 MIDI instruments, this is quite limiting without the use of 3rd party software.
For now I use LoopMIDI to connect Notion to S1 via the first 3 instruments and use TransMIDIFier on the 4th to connect my outboard gear. TransMIDIFier nicely splits the one "cable" into 16 channels, so I can address up to 16 pieces of outboard gear (synths).
It works. But I'd rather not be forced to use 3rd party tools to work around limitations like this. :)
Cheers,
Harmen