Just wanted to chime in on the use cases.
I have one B3 2TB running in the corner of the living room next to the router, which does torrent downloading of movies and tv shows, while also serving them via DLNA to the TV and media player-projector setup.
It also runs Logitech Media Server for my Squeezebox to play some of my music that is not available on the streaming services.
Then I use it for miscellaneous backup tasks; from time to time I copy some stuff from my laptop to the B3.
Oh, and a few times I have used the DLNA server to watch holiday photos on the TV with my girlfriend - even if the image quality is not impressive, it’s still good fun.
It used to do routing and wifi access point as well, but it wasn't quite stable and my debugging effort was fruitless, so I retired it from that task. Also it used to be a public web server, but due to the php security issues that caused it to be compromised once, I retired it from that as well. Time Machine backups over wifi also never worked 100%, so I dropped that as well.
I manage another B3 that runs as a gateway router in an apartment building, serving up a 100 mbps fiber connection to 80 apartments, while allowing me to SSH from home and perform simple network support tasks from time to time.
This one also runs some network monitoring and serves network stats to the owners via the web server, though it is not available from the outside.
Both these have been running 24/7 since we bought them in early 2011 without as much as a hiccup.
And as far as alternatives go, the only one I know of, is a RaspberryPi with big ol' hard drive/SSD. And they don't come in nearly as nice boxes as the B3.
What has changed for me is the same as for you - changed priorities - now I don’t find it nearly as attractive to spend hours trying to make the box perform some task or manually install security patches.
So bit by bit the possible use cases narrow down, for me - not because the box itself is getting too old, but mainly because the system needs too much maintenance work from my perspective.
-and I'm a former professional Linux server admin and network admin, so it's not like I'm afraid of the thing
The fine guys and girl have already commented on the state of development, and I have nothing to add - apart from expressing my gratitude that you are spending your valuable time doing this. Even if I’m not benefiting from it currently as I have issues with Gentoo and source based distributions in general, I think it’s fabulous that you do this. Big virtual high fives and thumbs ups for all of you!
In the meantime I’m cheering for Mouette to publish a easy peasy installer for the latest Debian and when that’s ready, I’m going to try to make the B3 run a ASP.Net 5 web server.