I've just committed a fix to sys/ufs/ffs/ffs_bswap.c::ffs_sb_swap()
(file rev 1.11) so that mounting opposite-endian file systems using
the FFS_EI kernel option should be significantly more stable than
it was, especially in the last 8 months.

I've also updated various tools in the tree that reference that
file (fsck_ffs, dump, dumpfs, etc).

Now you should be able to fsck, dump, dumpfs (etc) opposite endian
file systems, mount them and use them, and convert them with
'fsck_ffs -B newendian ....'

As usual, if you notice any problems, please send-pr.

(I noticed these problems whilst testing a file system image creation
tool I'm working on).

-- 
Luke Mewburn  <lukem@wasabisystems.com>  http://www.wasabisystems.com
Luke Mewburn     <lukem@netbsd.org>      http://www.netbsd.org
Wasabi Systems - providing NetBSD sales, support and service.