[Mark McLeod]

I tested with a globe motor load and the oddity disappears, so the odd collapsing waveform and the 2v drop seems to just be a characteristic of the adaptive gate Al brought up and the lack of a load as Alan suggested. It shouldn't affect normal operation.
There was a .15v drop through the Jag at 100%, but my battery is down a bit so that's not a full measurement.

The gray/tan jag gives full power at 100% with a load, and 2v less without a load.

With a load the waveform is the typical duty cycle switching between 0 and battery voltage for increasingly longer times as the throttle changes.

The CIM and the window motors show a cleaner 100% than the globe motor for some reason. Up to 100% everything about the power output waveform is identical. At 100% I see the periodic tiny drop to 0v on the CIM and Window motors, but for the globe the scope displays a messier plot.
The CIM also drew the battery down a bit more than the others of course.