JCat: I don't think the internal bluetooth will work on the Macbooks. I've looked into it, and there is one service that constantly loads BT into the operating system, such that Virtualbox cannot make use of it in the emulation. If someone figures out how, I'd be very interested, as I have all but given up on making the internal adapter work.
GR: In my experience, it takes between one and two hours to go from empty to a full charge. I have external battery packs laying all over my place that I received as promotional items - these will probably work, but they're flimsy and don't have close to the capacity as those you can purchase. Those battery packs allow the Crafty to charge for about an hour, although I am not sure how much charging got done in that time, given that the likely output was 1A and not 2A like the Crafty charger.
I'm planning on picking up a large capacity battery with a 2A output - seems to be about 20 bucks, so they are cheap. One of those I would imagine would double battery life, although as mentioned above, because the unit charges slower than it consumes power, you probably wouldn't get exactly 2 hours worth. But the more I play around with it, the more I'm realizing that for battery life, the Mighty is simply the way to go. I don't prioritize battery life, but someone that does would be better off just getting the bigger unit. I plan on using my battery packs as a backup source of power - I think it'd be too clunky and weird to use on a regular basis, due to the imbalance between charging and consumption.