fsync = true beneficial on ext3?

I'm curious what the consensus is, if any, on use of fsync on ext3
filesystems with postgresql 7.3.4 or later. I did some recent performance
tests demonstrating a 45%-70% performance improvement for simple inserts
with fsync off on one particular system. Does fsync = true buy me any
additional recoverability beyond ext3's journal recovery?

If we write something without sync'ing, presumably it's immediately
journaled? So even if the DB crashes prior to fsync'ing, are we fully
recoverable? I've been running a few pgsql clusters on ext3 with fsync =
false, suffered numerous OS crashes, and have yet to lose any data or see
any corruption from any of those crashes. Have I just been lucky?

TIA.

Ed