I use R24 as control surface to mix 16 tracks using Sonar 8.5 as a live track. Mics and guitar also. Can use FX built into Sonar, and eg switch reverb/delay on or off at end of song. ONLY DRAWBACK......I canoot get it to work when using Playlist in Sonar. Anybody else, or got over this problem please?

I also have an R24 - coolest box!  It would be my primary interface if it had better outs and more of them.  I haven't configured it as a Sonar CS yet, but I have set it up with others.
 
I don't know about the 16, but the 24 has a set of buttons for punch and markers above the transport buttons.  In the other DAW, these were fully configurable for anything you wanted them to do.
 
Check the zoom forum ... there is a decent amount of activity there with a lot of folks using the 16/24s in a variety of ways.