HN user
Thanks! Yes, please use the form on the site. We're pretty busy today with our launch, but we promise to get it to you ASAP. And yes, usage over longer periods of time is possible.
You make a great point, and we certainly don't want to exclude the in-between cases. We're still figuring out what those pricing tiers might look like, so if you've got an application that you're excited about, just let us know and we'll figure out a way to make it work!
You've explained it well! And you're exactly right, thanks to the accelerometer we get distances in real-world units. The trick is very closely integrating computer vision and inertial sensing. Images provide an external reference that can clean up the noise from the accelerometer, and the accelerometer provides absolute scale which you can't get from images alone. (I'm one of the founders, BTW.)
Better yet, here's a very relevant piece that tells you how to overcome the mental impediment to rationally considering situations with sunk costs involved. Basically, think about what you have to gain by changing things, rather than what you've already lost.
http://www.theatlantic.com/health/archive/2013/05/how-to-wal...