I'm using Teufelberger Tachyon (~11 mm). I have a rappel length of Predator but its not as radially stiff as the Tachyon so the rope collapses more under the pressure from the cam. IMO the Tachyon feels much smoother and consistent during the rappel and it's why I use it primarily. I have also used 10.5mm Teufelberger Platinum and it is very smooth running too.Glad you are safe!
What rope are you using? I've noticed that sampson predator take significantly more "pull" on the safeguard handle than Sterling htp. Not sure if it's the diameter or material that makes the difference.