The guys running live sound are definitely working with gear that links to iPads and enables them to move around and mix. They do a really great job, and I can say I envy them a bit.
I sometimes imagine what gear I would get if I wanted to try to run live sound regularly.
I don't own speaker stacks or monitors (my back hurts thinking about it).
So, when I try to help someone, I'm helping them with their equipment. I don't really know what I'm doing. I make it up as I go... notching and hoping for the best. Sometimes it works out, sometimes not so well.
I can say my friends who I record often encourage me to get interested in it. They'd love it if I took it on.
So, if there were some way for me to take what I have learned using Sonar and convey it into the bar scene to be able to get a great live sound all the time, I would. It is true though, that when recording live, I mostly use RME DigiCheck. I rarely use Sonar. Sonar is nice because it shows me the wave forms over time, but this is really the only reason I can think of to use Sonar during a live - record-only session. Obviously, if you want to use the Sonar Synths, you have to run Sonar.