Man that is a good grip.
In sport jiu jitsu, you dont have to worry about the punches but that is still a fantastic control position that should be used anyhow.
I am going to try that when we start from standing and trip my opponent backwards over an outstretched leg for sure.
Right, in sport jits you do not have to worry about strikes, but you can still use that same entry. The other thing to be cognizant of, is once you are behind them, if it's self-defense or mma, be sure to pin your head to their back/shoulders so the loose arm doesn't fire a huge elbow to your face when you are behind them with the 2-on-1! It's easy to forget. Nobody wants a broken nose :)
2 on 1 is a staple! OSS!