Would be nice to have a C download with a sample makefile to get people started. Also, some code samples on how to manipulate ports, timers and UART / SPI would be nice.
I'm planning to make an SD Music Player with an HifyBerry DAC+ Pro which has an I2S interface. For that I require a Teensy 3 (which has I2S on board). I'm currently still using Teensy 2 (AVR), but more and more boards are requiring 3.3V, so I'm gonna have to switch sometime in the future.