I also use a bluetooth PDA/GPS combination (Ipaq4700 and EMTAC Trine). The battery life of both units is in excess of 8 hours (extended battery on the Ipaq). I keep the Ipaq in a case which prevents accidental power-ons.
The screen on the PDA is fantastic, I think better than any handheld GPS unit I've seen.
Having said all of the above, I don't use this unit as a GPS. I use it to run "moving map" software. I've used it all over Europe with fantastic results : in fact (he says, tempting fate), I can't remember a single failure of this combination's hardware or software.
But for actual GPS usage, I have a panel mounted system. I wouldn't feel comfortable just using ANY handheld GPS without a backup (for the sort of mixed VMC/IMC flying I often do). And naturally, I only use GPS as a back up to traditional navigation technology, I believe that "NDB" really stands for "Navigational Dog's B*ll*cks", and I have a whizz-wheel wired to my underwear at all times, etc etc, blah blah blah ...
FF
