Very interesting. My wife's MAC freewheels just fine, but it is binding a little bit to where if you let off the throttle, there is a fairly loud winding noise and it slows down fairly rapidly. It doesn't seem to be affecting mileage very much, and sometimes it will actually go away and work just fine. I need to open it up again and inspect a little more.
We have the 8T motors and I'd really like the 10T motors for the hills and off-the-line torque (I really don't need to be going 31mph on a bike, too). However, I am concerned about exactly your issue, and that is durability of the clutch after many hard launches (although, I usually pedal a little bit off the line, and then hit the throttle). Maybe just get in the habit of switching to speed setting 1 for launches? You may want to consider re-programming your controller to reduces the speed settings. Default is 50% / 75% / 100%. Maybe do something like 30-40% for Speed 1? Just an idea as that will definitely add some life to the motor.
Edit: Just realized that newb already suggested the 30% idea. I have mine currently set to 42% / 61% / 100%, and Speed 1 definitely launches softer. I'm sure 30% would be very mild.
Two Treks, 4900 & 4300 (wife), MAC 8-Turn, A123 52v 11.5ah Triangle batteries