I've been toying around with throwing together an open-source clone for a while now. If you limit it to the 5S, the M7 abstracts away a lot of the hard problems you'd otherwise have to solve manually, and you can eliminate the server component by just having a flat-file Dropbox export (a la Nicholas Felton's Reporter app).
Anyone interested in maybe jamming on something like this should definitely drop me a line.
I rushed to buy the 5S for the M7. I was disappointed with the results. If you look at the offering of M7 apps, they mainly deal with step counting. The actual activity recognition is dismal (stationary, walking, driving, etc.) I had a demo of this working the afternoon the 5S came out. To get really good activity segmentation you need to monitor the accelerometer, not the GPS. This boils down to a signal processing problem, which I have no experience in. Any volunteers to tackle that problem?
Anyone interested in maybe jamming on something like this should definitely drop me a line.