[Dovecot] LDA vs maildrop... LDA *and* maildrop?

[email builder]

We're considering a move from Courier to Dovecot.  So far, looks like
it's not too bad, but the most challenging obstacle is what to do about
our local delivery.  Factors:

1. we use a lot of maildrop "features" that are impossible in sieve 

without piping to an external program (would rather not re-write our
working maildrop scripts in another language)

2. would love to try dbox

3. we use IMAP/Maildir++ quotas (looks like with a little finesse
it's possible to get maildrop and dovecot to play nice on this
account, yes?)


I saw it suggested to just call LDA from maildrop for any maildrop
"to" commands (hmmm, what about "cc"?) here:

http://article.gmane.org/gmane.mail.imap.dovecot/56120

How much overhead will this take?  Would it be possible or
advisable to use LMTP instead if that would help?  Is this
idea just too crazy?