The thing about it is if you do the math and you look at the change in speed or torque, you will get more torque and speed out of a unregulated system 5.6 volt reg and 6.6 volt unreg. The change in speed or torque for an operating range of 6.0v to 6.8v is a little over 10% but still better than a regulated supply. It is just not needed and most of us will not see the difference in servo speed from lets say .1 second over 60 degrees (6.8 volts) to maybe .12 seconds over 60 degrees at 6.0 volts.