OK, so I'm now sold on getting an iPad2. I gather that an external GPS is pretty much a given requirement. Options appear to be a Bad Elf plug in device at £100 but with a risk that the plugging in feature will eventually create a bad contact for the interface. Or a Garmin Glo that communicates via Bluetooth. I have actually heard of Bluetooth.
Another thing that popped up in discussion was "retina" display. I thought this was just a batter screen, but it seems that it represents the difference between the dinosaur technology of the iPad2 and the current technology of the iPad 2. Confused? Me too.