Regarding the Bad Elf, I agree with a64pilot. I had an earlier version of the plug-in type Bad Elf and used it with a Wi-Fi
iPad 2, but it always felt a bit cumbersome and made the
iPad harder to handle. Had to take care not to bump the Bad Elf, the iPad wouldn't fit into the waterproof pouch any more, and
charging while using the
GPS was possible but fiddly because one has to use the (short) mini-USB cable supplied with the Bad Elf. As for performance, the
GPS worked fine with
navigation apps, but getting an initial fix seemed quite slow and sometimes required unplugging the unit and plugging it back in to get it going. When I upgraded my iPad, I got a 3G model with the internal GPS chip, and never looked back...