I did it. Is it possible to undo it?
You can only undo it with a factory data reset. There is a notice/warning that says that as you go through the encryption process.
I would undo encryption if I could. Takes too long to boot up...seriously almost three minutes. Don't reboot often, but that's really too long. Then, when it's in your pocket and and your phone mysteriously reboots, it's stuck in 'limbo-mode' and you don't know it cuz you have to put your security pattern in.
That was my huge pet peeve about encryption on Android. Maybe Marshmallow is better. However, I do know that on my Droid Maxx, the phone beeps/vibrates every so often as it is waiting for the passphrase to unlock encryption on a bootup if you haven't entered anything. Does the Turbo not do that?
The Maxx is stable for me and rarely spontaneously restarts, and whenever it does so after I encrypted, the phone does not do a full reboot - it is more of a restart of the Android OS, because the phone never prompts me for the unlock password (it just goes to the normal lockscreen.) So, obviously, the phone did not lose power or go through a full startup cycle; if it had, the storage would be locked.
If you're not Secret Squirrel, I wouldn't recommend it. (Other than boot up though, I noticed no difference in performance)
I wouldn't say that I am "secret squirrel", but encryption will prevent a stolen or lost phone from having its data read. And I have information not only about me, but about my friends as well - their contacts, what they say on Facebook, private messages. I definitely do not want to be the cause of a friend getting harassed because of information gathered from my lost phone. A normal lockscreen with a setting to erase the phone after 10 attempts may be good enough, but encryption is slightly better - with those caveats you've discovered.
Obviously, the iPhone does this better.... (though, again, it may be that Marshmallow is better. I don't know.)