The 911 issue seems small compared to the threat of totalitarian surveillance states, at least to me. I also have the strong intuition there's some way to implement emergency calling anonymously or pseudonymously using cryptographic trickery. In the end, I prefer living somewhere I can change the IMEI if I want

And a hint--I believe it's actually quite easy using an edXposed module if you want to root your Android phone.

Of course, then you've got a rooted phone, which is less secure.