I run about 5-6 instruments max per instance of Kontakt 5, and never ever use simple instrument tracks.  They just do not work for the multi-timbral synths, from what I understand.
 
So, especially for Kontakt, I use separate audio tracks and separate midi tracks for each instrument, and use the Kontakt Batch Functions in the Output Section to set up separate stereo outputs for each loaded instrument, then insert audio tracks and midi tracks for each instrument in the Track Pane in Sonar, and route accordingly back to the corresponding instruments in Kontakt.
 
 
To take the above even farther, for common combinations of loaded instruments in Kontakt, I will select the audio and midi tracks for that instance of Kontakt, then create a Sonar Track Template, which will save off all of the audio and midi tracks I set up for that instance of Kontakt, as well as the multi-rack and the loaded multiple instruments and their settings in Kontakt, all as part of that track template.
 
Then, for new projects that use the same or similar instruments, I just insert from the saved Track Template, and all of the routing assignments, tracks, and the Kontakt instance, are all loaded into the new project with just a small number of mouse clicks.
 
VERY handy.
 
Hope the above helped - please post back if you have any questions about any of it.
 
Bob Bone
 

Bitflipper, Good information.  I have had conflicting advice from different sources, and that advice varies by VI (Kontakt, Vienna, Hollywood/Play, etc.).  Thanks.

Single instance for each instrument here for Kontakt. It suits my work flow especially if I'm writing/editing for Orchestra.

Bibs

Honestly I see no advantage in having multiple instances of Kontakt for any reason.
 
If you can have multiple audio outs which Kontakt can do the notion of having one Kontakt per one instrument seems to me to be inefficient and wasteful.  However each to his/her own. Its your choice. 

Thanks for all the input.
 
So many variations and reasoning.
 
Lance

John
Honestly I see no advantage in having multiple instances of Kontakt for any reason.
 
If you can have multiple audio outs which Kontakt can do the notion of having one Kontakt per one instrument seems to me to be inefficient and wasteful.  However each to his/her own. Its your choice. 

It's just slightly quicker to set up and keep track of what's what, that's all, I think. Click insert synth, choose Kontakt, pick a sound. Rather than create a new midi track, route it, open Kontakt, add a sound, choose the correct output, label the output, etc.
Just laziness but my computer seems not to care so neither do I.

So, did you get all that? I personally like using multitimbral , single instance for soft synths whenever I can for track economy and I feel the performance is better. The more softsynths I open up, the more I feel I'm taxing my system. When using multiple outs, let Sonar open them all, you'll use 'em. Bitflipper's point is well noted. Multiple instances allows you to freeze any given instance, if necessary.