TTS-1 / multiple instances or not?

Seems to work OK. Here is an image of a project created from a project template containing one instance of TTS-1.

 
Piano is on MIDI channel 1 and audio is set to TTS-1 output 1
Organ is on MIDI channel 2 and audio is set to TTS-1 output 2
Bass is on MIDI channel 3 and audio is set to TTS-1 output 3
Drums are on MIDI channel 10 and audio is set to TTS-1 output 4
 
The image also shows the steps to assigning the 16 MIDI channels to the 4 TTS-1 outputs. Click the system button on the TTS-1 UI, then click the option button on the System Settings dialog to see the output assignments.
 
I used the drop downs in the MIDI tracks to make channel, bank and patch assignments.
 
I doubt whether using TTS-1 multitimbral or not is much of an issue with modern processors.
 
 

The TTS-1 will accept 16 MIDI channels in, so there are a couple ways to do this.
 
Easiest - SONAR automatically inserts TTS-1 if you open a MIDI file and have no MIDI output... so you can open a 16 channel MIDI file with no MIDI output assigned in SONAR and delete the MIDI data.
 
Harder - Inserting TTS-1 will only give you one MIDI input track. Manually insert 15 more, but you also need to assign Output=TTS-1, and each channel by doing this. Channel 10 is typically the drum channel. Assign the instruments in TTS-1 as desired.
 
Regardless of how you do this, I recommend doing this in a folder, and then saving that folder as a "track template" when done, so you only need to do this work once.