Paul, did you test how many shots you get with a fully charged battery with vs. without the di-GPS?
I have read the positive reviews by Moose Peterson & Bjørn Rørslett. Bjørn mentioned the battery drain problem but apparently it was solved with the GPS feature firmware in the D300/D3/D700 & with new di-GPS models with a lower power consumption.
Do you leave it on or do you switch-it off between shots taken say, 15-30 minutes apart, like when hiking for example to save power at the cost of a longer acquisition time?
Bjørn mentions also the lack of 10 pin connector for a remote or cable release but the newer model you linked to now has that feature.