Disk Utility encryption vs. FileVault 2

I'm doing a clean install of Lion onto my iMac and I would like to have full disk encryption. I'm booting to a Lion DVD and have just zero wiped my hard drive as "Mac OS Extended (Journaled)". I see an option for format as "Mac OS Extended (Journaled, Encrypted)" and was wondering if there are any differences or advantages/disadvantages to encrypt the boot disk in Disk Utility rather than FileVault 2. During research of FileVault 2 I discovered a drawback; one must shut down the computer to take advantage of the encryption:

From Macworld:

"While your Mac is booted, anyone with physical access to the computer—someone who sits down in front of it, breaks in remotely (however unlikely that seems at the moment with a Mac), or runs away with your laptop—could access your data. So get used to shutting down your Mac when it's not in use, or when it's out of your control, rather than putting it to sleep."

Any info much appreciated!

All full disk encryption behaves this way. There is no other way to use the OS unless it is unencrypted at boot time.

When doing the FileVault2 method you are prompted to either store your key with Apple or write it down. This is in the event the OS no longer boots and you need to retrieve files from an encrypted drive.

The nice thing is that the pre boot password is also your login password and you only need to authenticate once to the Mac to get logged in.

No matter how you encrypt your drive, when it is booted it is decrypted.

You can create encrypted disk images that can be mounted when desired for storing and accessing secure data but they can be accessed the same way when they are mounted.

The nice thing about FV2 is that time machine will function while you are logged in versus FV1 where you needed to be logged out to get a backup up.