comparing directory trees - mtree?

["Tom Ryan" <tom.ryan@whitehorsestrategic.com>]

Testing my backup (more acurately, my restore...), I want to compare two
directories recursively.  I'm convinced that mtree can help me with this,
but I can't find what I need on google/archives/man pages/etc.

I've been trying this:
  $ mtree -cp /path/one | mtree -p /path/two | tee /tmp/mtree.out

When I do this on:
  $ mtree -cp /path/to/a/smaller/bit | mtree -p /path/to/backup/bit
I get good meaningful output.  When I try that big one I seem to get a lot
of garbage.  I get a lot of:
  missing: /path/to/somefile
where file *does* exist in both!  I'm confusled.

I've also tried using diff, but that rapidly dies... out of memory.  I don't
think diff is appropriate, anyway... I don't need to know what is different,
I just want dates and filenames.

thanks,
Tom.