Oh, I forgot to mention one detail you will want to know about. The initscript will get overwritten the next time you upgrade the RPM (it is not a configuration file, after all, but a program and part of the package and subject to change from time to time). Thus if your postmaster quits responding when you upgrade next, you'll know why.
Perfectly reasonable, but along these lines (at least for the rhel/centos/fedora rpms) why not seperate things out like what's done with bind, apache, nfs etc, and put any options like -i into an /etc/sysconfig/pgsql file?
-- Jim Perrin System Architect - UIT Ft Gordon & US Army Signal Center