Also, regarding the SONAR aux track, SO treats Folder tracks almost like busses, whereas SONAR treated a folder just as..well a folder.
If you create a folder track with several tracks within, you can make sure that's visible and able to be opened and closed in the console view as well. So the folder and buss function almost becomes one in the same. You can then apply any effects or inserts to that FOLDER ( like an aux track or traditional buss).
This allows me to use SO's (Folder/Buss) combo much the way I used Aux tracks.
(Sorry if my explanation is not totally clear..I'm still a newbie with SO but the alternative to AUX tracks was one of the first things I looked for as I used them a lot. The "Folder/Buss" relationship allows for much of the same functionality from what I can see)