Bad Seed Tranquil ROM fixed BT issues with stock
FWIW: I was having issues with my stock DNA ROM connecting-up to my car via BT. It would easily connect for hands-free, but it failed to xfer the contacts/phonebook, and it would not transfer/update txt messages to the car. The former issue I considered "major" to me, the latter was a "nice to have if I could get it to work."
The Tranquil ROM (and possibly others like newt's, I don't know) solved both issues. It wasn't the reason I tried the ROM, but what a bonus!
Thanks to the devs!