[Dovecot] Quota Limits Newbie Question

I have Dovecot 1.0 running on a SLES 10 mail server using postfix 2.2 and amvisd-maia. The mailboxes are stored in Maildir format with all the domains and users stored in a mySQL database. I would like to implement quotas for the system and have looked at the VDA patch for postfix and/or quotas within Dovecot. Any advantages to either? From what I can see from a couple of searches, Dovecot does not appear to respond either to the sender or recipient when they are over quota while one can set-up postfix-vda to do so which would be of value.

Thank you for the time and input.