Well, the updated firmware is both good and bad.
The good: both units are much more stable, and although I did have one crash on the DLNA unit when writing a file to it, it has not crashed otherwise (until just now, see below).
The bad: my BitTorrent/Backup unit will not allow me to copy off a file that's more than about 350mb. Anything larger and it just quits during file transfer. The unit doesn't crash completely, the file transfer just hangs. I had to use FTP and cancel/resume to transfer off a bunch of files, it was the only way to move them. I've tried rebooting my machine and the unit itself, no change. It doesn't matter whether I'm trying to copy one file or a group, it does the same thing - somewhere between 350mb and 400mb the transfer just quits.
I was able to copy large files off the DLNA unit.
Right now the DLNA unit is running its backup to the Backup unit, so I'll report whether it was successful. It hadn't been able to complete a backup for some time because of the previous issues. However, once the backup started the DLNA unit's web GUI became inaccessible and it is NOT visible in NAS Navigator so it appears that it crashed during the backup. I have no idea whether the crash is because the DLNA unit crashed or because of a problem with the Backup unit and the large file transfer issue.
I'm about done with this. These units are obviously unstable, many people are having the same kinds of issues, and Buffalo has no idea how to fix them. Either the firmware is garbage or they were shipped with bad NIC hardware. Either way this isn't worth my time. Buffalo won't be getting any more of my money, and my customers will be advised to purchase other solutions.