RE: 150 meter rule.
The resolution of the ET GPS appears good enough (usually using 9 sats). For example, one can easily determine "roundness" of rolling circles (or 8's) as well as size, as these are in a horizontal plane.
Vertical maneuvers are more difficult, some of which lies with the ET viewer. The data are compiled so as to present a track relative to time and we fly a sequence in the same space (box). Sothe track of each maneuver overlays the previous -it ends up looking like chicken scratch. That means each maneuver (or a couple at most) must be done individually, which is very time consuming.
Some work has been done to translate the data into a 3D "box" which would allow an entire sequence to be scrolled through on a maneuver by maneuver basis referencing the time base. It would also be possible to look at a maneuver from various viewpoints. I'll let the persons working on this to comment further if they wish - but work in progress.
Another trick that might work is to switch the logger off/on in flight(which starts a new data group) to limit the overlaying of maneuvers during a sequence - haven't tried that yet.