We’ve been working with Atmel AVRs for quite some time now. All in all, it’s a nice architecture, and I can’t really remember why we decided to try out ARMs, and specifically this Cortex-M3 chip. Maybe it’s their built-in USB bootloader. Or their lower price. Or higher processing power.
Luckily, a few of these chips just happened to be lying around, and the board designs are available. Not so for all the components, though – specifically, the 12 MHz crystal. Which wasn’t hard to replace. Yet, after a few tries to re-route for homebrew manufacture, it became evident there’d be one via too many if one wanted to keep the nice GPIO layout. So it had to be shipped to a PCB manufacturer.
Perhaps this won’t be faster than Adafruit, but at least it’ll be cheaper. Thanks to the fact it’s all open-source (or whatchamacallit). In case you’re interested, here’s the modified version at GitHub.