Do you know if they address I/O reordering within the scheduler? For example transaction implementations often require that writes (distinct file system calls) hit the disk in a particular order to guarantee a sane state for the database. Prime example is the GNU bug for gzip:
The the writes to the `foo.gz` file have to hit the disk before the unlink but the I/O scheduler can reorder these potentially and a badly timed crash could result in data loss. Note that journaling doesn't fix this issue because the transactions are distinct too.