Logging sailplane flights

I've been doing some sailplane flying out at Invermere, BC lately, and
recording my flights using a variety of tools. Oftentimes there'll be
a Colibri flight recorder in the glider – it's an IGC-certified GPS
and datalogger. But also I often fly with a Garmin Venture cX, which can record flights, and occasionally I've flown with a Wintec WBT-201 Bluetooth GPS/logger.

Here's a trip report of a flight on July 14th, recorded by both the
Wintec and the Garmin. If you want to compare the recording behaviour of the two loggers, download the two .gpx tracks and then open them both in a program like GoogleEarth.

Here's a screenshot of GoogleEarth showing the two tracklogs. I raised
one of them (and coloured it red) in order to separate it slightly so
as to be visible. Note that there is pretty good agreement between the
two tracks except at the end (when the Garmin inexplicably shut off).