Is there a way to use both mbox and maildir formats as local delivery
mode for different users or subdomains in postfix at the same time ?
Postfix is working fine, but I have not yet found any way to deal with
per-domain (preferred) or per-user delivery mode setting. Did i miss
some part of the docs?

Or do i have to build a (IMHO very ugly & costly) solution with routing
between two postfix instances on the same host? Any other tricks to
build multiple individually configured local transports?