I've been using Synology NAS devices for some time now and I'd definitely recommend them too. They have great support, even for their 'budget' systems, and provide many years of software updates and fixes. Their main web interface doesn't suck, and they also support SSH and command line management of the devices too.

I've not invested in backup power, but this is one area that I'm a little skeptical of... nowadays all filesystems are supposedly advanced (log-structured records, etc) so in the event of power loss, in 'theory' you should only be losing at most a few minutes of work, depending upon caching. i.e. stuff that hasn't yet been written to disk might be toast, but everything else should be safe. Or can worse corruption still happen?

(quick edit to add: I'm not saying that backups are a waste of time, not at all, just that I'm questioning having a short battery power-supply backup)