I've been very busy lately, but have managed to get a test quadcopter thrown together to test new features and improve the code:
I am using the SparkFun OpenLog to print data to a spare serial pin on the Teensy, which is then dumped into an SD card as a .txt file onboard. Super simple!
Here is some sample data showing the control response. Overall, I am very happy, but this data is already giving me ideas on how to squeeze out even more performance!