I have 4.5 GB. Since learning I can use multiple standalones I have maxed out my RAM for the first time. I used to open KS as a plug-in in DP. A second instance sucked up so much CPU it would often lock my system (dual 2GHz G5), and to try to use convolution with 2 instances - forget about it! Convolution on 3 instances no problem now. Definitely happier with this "new" method. Makes me consider getting some more RAM.
I wish I could take credit for the cleverness, but it was posted here a few weeks ago. The thread seems to have vanished. Yes, you get 4 ports times 16 independent MIDI channels for each K2 instance.
I'm not sure how to route the MIDI through on Sonar, but using DP it's very simple. DP allows interapplication MIDI routing. Publish a new MIDI out patch (16 channels) in DP and match it up to the same name in K2's MIDI setup window. Using this method you can no longer freeze tracks in your sequencer as the audio is coming out via K2's outputs. I use Soundflower to reroute the audio back to DP. Assign up to 8 simultaneous audio channels and hit record - (somewhat)instant stems in a single pass.
Again, I am not familiar with Sonar's capabilities. I seem to remember reading that you could use some small VST freeware/shareware program that routes MIDI from your sequencer to K2.
This method has been working a lot faster for me than the VST/AU plugin method.