I've been debating it. For how I use my phone, the encryption is a false sense of security.
The email can be had from the servers my accounts are on, I use some cloud services that will similarly serve up my data with a warrant.
Encrypting my phone would just slow down the police, not stop them. And if stolen, I don't keep anything valuable or risky on the phone anyway.
When the ROM choices start rolling out, I may be more likely to encrypt depending how it's baked into the ROM.
One last caveat. Depending how you set up your SD card storage in Marshmallow, your SD card may or may not be encrypted. My understanding is that if you set your SD card as internal storage, it will be encrypted. For my purposes, that's not useful as I need to use the SD card on multiple devices.