If you're interested it's probably pretty easy to port the TeensySaber software to your setup. The only part that isn't already supported is the MPU-6050.
I haven't taken a look at the TeensySaber software, but I'm sure you're right. If you're doing any sensor fusion, the NXP seems like a better solution. Getting the DMP to work on the MPU-6050 is a bit of a pain and it seems to have a lot more drift compared to the one on the prop shield. That being said, I ended up not needing absolute orientation anyway.
I'd happily add some MPU-6050 support if you'd be willing to test it.
The teensysaber software doesn't use any sensor fusion, never saw the point of doing that.
Teensysaber uses a cooperative lightweight threading model, so the standard libraries probably won't work, but it's pretty easy to fix it.