Hmmm, just back from my weekend in the Peaks. It would appear that the m600 with external BT GPS dongle performs better, battery life wise than then Trinity using internal GPS.
I went for a 6 hour bike ride on the Friday with BT on the entire time. By the end of the ride the phone battery was down to about 50%. We did a 7 hour walk on the Saturday and by the end the battery was down to about 40-45% (after recharging to 100% over night of course!). Again with BT on the whole time. The GPS did get a little confused when we went into a pub for lunch each day but that's not a great surprise. Other than that it held its signal fine the whole time. Oh, and I had it on 195MHz speed (default) the whole time.
So, it would appear, from very unscientific field tests, that the Prophet using an external GPS is much more efficient than the Trinity with internal GPS. However it was a bit annoying to have two devices (GPS dongle and phone) rather than just the phone.
Would love people to post their experiences here so we can build up some more empirical evidence on the subject....
Edited by Blakey, 02 April 2007 - 08:57 AM.
I'd rather be defenestrating chaos mages...