[JohnR]

Is anyone using FileVault 2 for a) backups or b) internal drive?

It seems that for (b) it's simpler to format the drive as encrypted first, rather than try to encrypt a full drive (never seems to move out of the "Encrypting" state).

I'm wondering if Mavericks makes any changes in how things work.

[skunark]

I've been using FileVault 2 on my new MBP, didn't notice a speed change at all.   For the internal drives, you don't format encrypting, you just enable/disable and in the background the system will encrypt/decrypt.   

[JohnR]

HI Jim, I've been using it on my backup drives for a while now, haven't been game to try on the system drive yet. Should just bite the bullet, thank you for the input!

J