each time i've considered that question (each time
i've configured a new file server) i've eventually decided
in favour of using the pseudo-worm driver.
it isn't more resilient in the face of certain crashes
but it might be slightly more likely to detect an inconsistency
sooner rather than later (or at least more cleanly).
i could be wrong but i suspect a few supporting commands rely on getting
a read error for blocks not yet written (cwcmd prchain might be one).

i'm glad i did keep the bitmap the last time, for another reason.
the written-block bitmap also turned out to be quite
useful when copying the existing structure to a real
worm jukebox, since it said which blocks had actually
been written, and helped to set precise limits for the copy.

another useful hint when copying a
pseudo-worm to a new file server with a real jukebox
and a new set of cache discs with a different structure is to do
	cwcmd savecache
on the file server, and {disk/exsort -w} before
starting the copy.  that way, cwcmd loadcache
will reload the cache on the new file server
with much less jukebox activity (and that's an understatement).