How often do you update them? Do they autoupdate themselves like an apple airplay router could? Has that gone wrong?

I let Debian install security updates automatically; they haven't broken anything so far. The devices are only available from the LAN and only expose SSH, Bonjour, and the actual Airplay protocol server, so I'm not too worried.

I wrote a systemd unit for the daemon so it comes up again on a power cycle, and encapsulated the config in a puppet repo for repeatable deploys (did the first one by hand, developed puppet and used it for them both when it came time for the second installation).

Hardest part was WiFi, you have set some config flag to keep the dongle from falling asleep when idle. But I caught that on the first day of deployment, and it hasn't been an issue since.

If you don't want a Linux project or an expensive project, there are cheap Bluetooth audio receivers on Amazon.