pfsync + pfflowd + flow-tools (ifconfig maxupd)?

[vsavichev at wesleyan.edu]

hi all,
we're trying to build pfsync centric accounting system. Our plan is
to use pfflowd to emit NetFlow datagrams to work them out within
flow-tools. E.g., using flow-receive we get SOMEFILE which
can be further proceesed by flow-export or alikes. We found
that SOMEFILE gets occassionaly updated. man pfsync says that
state infomation  refreshment is condensed which is controled by
maxupd parameter to ifconfig (equal by default to 128).
For some reason FreeBSD (5.3-stable) version of ifconfig has
no maxupd option, OpenBSD does. So we believe now, pfsync iface
in that incarnation of FreeBSD has no way to change this parameter
and hence to fine tune state information update frequency.
Is that so?
Vlad