Hretting,

You say "datalogger" and list some devices. Unfortunately, none of
those devices qualifies as a datalogger in the true "soaring" sense of
the word.

That is, none of the devices that you mention can be used for soaring
badges or contests. I am unsure about OLC. Plus, as standalone GPS
devices they aren't optimized for soaring (tasks, turnpoints,
thermaling, etc). To get all that, you need a FAI secure flight
recorder and a PDA for moving map.

One option is a PDA with soaring software and a GPS card.
http://cumulus-soaring.com has some examples. The soaring software
will log your flights in a way that I believe will work with OLC (but
not badges and most contests).

Anyway, I'd love to see a one piece, standalone, Garmin/Etrex like
handheld device that has a moving map, with soaring optimized software
and FAI certified (really wishful as it needs an altitude tran
$ducer). I think that some handheld GPS manufacturer should see the
light and make their platform "open" (like cell phones are moving
towards, iphone, Windows Mobile, Google phone) so that developers can
come up with way-cool applications for nitch markets....like us!