I'd like suggestions from experienced users on GPS data loggers for
photography.

Oddly my Sony a900 does not come with a GPS data input to tag images
with position and time. I would have though Sony would have added this
as a natural with their own GPS logger. (Sort of proves the ex-Minolta
guys are keeping their distance from the gadget boys at Sony).

IAC, I would like a logger that:

-has a programmable interval, or a push-button "log this pos/time".
-logs position, altitude, time (UTC) and optionally
-speed, track-made-good
-12 or more channels
-24 hour or better battery life - and/or - rechargeable (car or wall
charger)

-light enough to wear under a hat - though will probably be clipped to
the backpack.

-software (Mac preferred) that will automatically EXIF tag DNG files
directly (I convert from .arw (Sony raw) to DNG when I upload to the
computer. [I set the camera time in UTC to eliminate timezone/DST
issues]. (I don't mind using 3rd party s/w, esp. if it's free!)

Options:

-heading recording (from a magnetic heading sensor, or integrated).
Note HEADING is the orientation, not the GPS derived track-made-good.

-baro alt.

-external antenna (passive or active).

-may use same sensor for cycling, hiking, etc.

-may use same sensor for vehicle position logging.

-annotation capability