Conservative postgresql.conf made by initdb?

In postgresql.conf generated by initdb shared_buffers is set to 32MB
even though there was more available (see below; also ipcs shows
postgres is (and will be) the only shared memory user). Is this enough
or maybe it's less than ok? I don't know. What I do know is that MySQL
4.0.x uses 500-550 mb RAM for similar access patterns. Also,
max_connections preset to 40 is more than ok for our case. Is
max_fsm_pages = 204800 OK ? Should I increase it if I expect 15-20 gb
disk usage by db?

FreeBSD 7.0-BETA3 PostgreSQL 8.3 beta2

sysctl settings at the time initdb ran more or less resembled the
recommendations given here:
http://www.postgresql.org/docs/8.3/static/kernel-resources.html#SYSVIPC
namely:

kern.ipc.shmmax: 134217728
kern.ipc.shmmin: 1
kern.ipc.shmall: 32768
kern.ipc.shmseg: 128
kern.ipc.shmmni: 192
kern.ipc.semmns: 60
kern.ipc.semmsl: 60
kern.ipc.semmap: 256
kern.ipc.semvmx: 32767

Maybe I should increase shmall/shmmax and rerun initdb to maximize
performance of expectedly 25-30 concurrent connections, which are
"persistent" and hence many of which are idle at the low hours?

Thanks.