[jsheard]

It's $200 for an extra battery, all of the accessories have a steep early adopter tax. Besides, has anyone confirmed whether or not the AVP has an internal backup battery so you can hotswap the external battery without rebooting it?

[nonfamous]

According to the linked review, hot-swapping is not possible - disconnecting the battery powers down the device.

[jsheard]

In that case if you want to use it for many hours without access to wall power you're better off buying a generic USB power bank and plugging that into the Apple battery. Very elegant.