I did some tests using a modified version of a script called BlackBox which I found elsewhere on the forums to capture the RPM cut and G value.
Chart is attached. It seems the cutout is set to 0.5G and seems instantaneous. You can see the 'highest' G-value cut, the third red line from the left. Others are just more examples. 0.1G it definitely ain't.
The chart shows RPM vs G-force and the G-cut is easily seen just before the characteristic RPM overshoot that occurs after it recovers.
You Merlin flyers need to vote on this unless its already in hand. Many very minor bugs and features have more votes than this.
http://www.il2bugtracker.com/issues/230