The only Achilles heel for this is getting the data out and doing some real analysis of what your sleep cycles are, how your fitness levels trend, etc.
Hopefully in the near future, they will come out with something, but thus far, the data you see is quite limited.
I managed to extract the raw minute-by-minute data from the Band using some hacky tricks. I was thinking of posting a howto, but trying to check if it runs into problems with the CFAA/DMCA. Might post something tomorrow after making sure it's legally sound.
I'm curious whether you decoded the binary protocol/blob or have just been poking at the API (where just about everything is pretty convenient JSON). I've done the latter but haven't broken out my Ubertooth yet for the former.
Re: DMCA - there's a reverse engineering carve-out for interoperability. While I guess MS could abuse either CFAA/DMCA to slap down RE, it seems like it'd be a pretty bad PR move.
A lot of my notes aren't super well organized (and wouldn't make sense w/o scrubbed captured flows) but I just posted a comment on your post thread talking about the BTLE as well as the remote API stuff.
The only Achilles heel for this is getting the data out and doing some real analysis of what your sleep cycles are, how your fitness levels trend, etc.
Hopefully in the near future, they will come out with something, but thus far, the data you see is quite limited.