You may also want to take a look at http://mail.tekscan.com/nomailboxes.htm
It is a little dated, but all the points still hold true.
Also, be aware that BrickLevel backups are useless for disaster recovery purposes. You NEED stores level backups for that. You may decide to do brick level for a few high profile users, but not for every body
If you have the diskspace on the Exchange Server, you can restore a stores backup to the Recovery Storeage Group and get anything you need from that.
(Looks like Veritas/Symantec have improved Brick Level in v10, but there were lots of folks who had real problems when trying to do a single mailbox restore in v9.x)
And a final comment. ThroughPut for brick level backups is horrendously low. You may get 400-500 MB/min for your stores backups and 25-30 for the bricklevel