As I've not yet found the time to set up a mailing list, feel free to ask questions here.
I'll try to answer them and everyone else please try to answer them, too.
Is the TeraStation very loud?
The temperature regulated fan inside keeps the noise down, but the 4 hard disks produce a lot of vibration.
Are there any firmware updates?
There are no non Japanese firmware updates for the TeraStation at this time according to Buffalo tech support.
I want to avoid soldering. Is is possible to become root without serial console?
Creating your own firmware image with SSH installed and a known root password is possible. See here for a guide to extracting the firmware. Another method would be to remove the disks and modify them directly.
I don't want to open my TeraStation. Is it still possible to become root?
Yes. See the previous question regarding modifying a firmware image and applying it.
There might be bugs in the software used, but we don't know.
The web interface filters all critical characters. So, unlike the WRT54G(S), the TeraStation can not be hacked from the web interface.
It should be possible to hack the firmware updates, but there are two "problems":
- there are no firmware updates available outside Japan.
- the hard disk images inside firmware updates are encrypted zip-files.
Has anyone successfully replaced the TeraStation's firmware with a different Linux system?
I've chrooted into a Debian/PPC. That works fine once you're root.
Can I install or replace Linux applications on the TeraStation?
No problem, once you're root.