There are many others, but these are the ones I know best.
Heard from time to time.
Uppsala University (UU) runs three separate AS all behind it's own Bifrost router pair..
and all of them are on the Sunet top-10 traffic list.
I think they do work.
You (usually) can't hot-swap hardware (i.e. adding a new NIC will spoil your uptime)
Hardware do break sometimes, no matter what brand it is
Use well known hardware (or make sure you test it long before you start depending on it)
Use them in pairs, both for redundance and maintainance (it won't save your uptime but it is still a good idea:-)
If placed on noisy power lines, use an UPS
Keep backups - even USB sticks fail
That's all for now