Reinject to Postfix, or just send on to LMTP?

[/dev/rob0]

Please forgive what might be a too-basic question. I'm setting up a 
new system with Postfix/virtual delivering to Dovecot LMTP. I'm not 
quite understanding if there is any benefit to this design:
	Postfix -> Amavisd-new -> Postfix/reinject -> Dovecot LMTP
as opposed to this:
	Postfix -> Amavisd-new -> Dovecot LMTP

I understand that I'd need either two amavisd processes or policy 
banks on alternate ports for submission and sendmail, and I'd still 
need that reinject smtpd for the outbound mail:
	Postfix -> Amavisd-new -> Postfix/reinject -> remote SMTP
But I don't see any reason why a policy bank can't handle that, with 
forward_method in the appropriate policy bank: LMTP to localhost for 
incoming, SMTP to Postfix/reinject for outgoing.

Postfix would route incoming mail to amavisd via a virtual_transport 
setting, and route outgoing to the other amavisd port (i.e., 10024) 
with a check_client_access static:filter,smtp:[127.0.0.1]:10024 
restriction. (I'm not sure if the comma will work in a static: map, 
but if it doesn't I know several workarounds. :) ) I'd only need a 
content_filter setting as an -o on pickup(8).

Does this make sense? I hate the log clutter of the double-pass 
through Postfix, so if I can avoid it, I will.
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