As a serial distro hopper, my only complaint about using Debian Stable over the years is hardware compatibility. As the author noted, Stable isn't for the latest and greatest hardware. This was especially true for me a couple of years back when trying to run Debian Jessie on a then-new Intel Braswell based system. The video driver as shipped was unable to render at any resolution above 1024x768, and there were severe artifacts especially with certain fonts. Switching to Ubuntu cleared up the issues (newer kernel and newer X11 driver).
That said, Debian Stable is an ideal desktop OS for older hardware. I have a Mac Mini from the first generation of Intel Macs, upgraded to a Core 2 Duo CPU, that runs BunsenLabs Linux (based on Jessie and a 3.x kernel) just fine. In fact, it's one of the few Linux distros that still supports that 11 year old machine, long after even Apple left it behind.
It's literally the only distro I can run on my two My Book Live mini-file servers being powerPC and all. Have to run a patched kernel though.
Couldn't see running it as my desktop distro since I like to fiddle with stuff and having an older compiler and python isn't really all that desirable. Back when I hacked on blender I was even having a hard time keeping up on 'bleeding-edge' fedora since one of the main devs liked to upgrade to the newest python release as soon as it was out.
Debian has dropped PPC support moving forward, so you're on borrowed time. You may want to look into OpenBSD or NetBSD as a backup plan if you intend to keep that hardware long-term. I've found OpenBSD to be nearly painless to maintain and not too much of a learning curve (admittedly coming from Slackware being the Linux distro I cut my teeth on nearly 20 years ago).
That said, I don't know how difficult it would be to install a non-Linux OS on that particular device; I know it was designed for and shipped with Debian. I've had success installing the various BSDs on all kinds of obscure hardware but I've yet to get my hands on a MyBook Live.
That said, Debian Stable is an ideal desktop OS for older hardware. I have a Mac Mini from the first generation of Intel Macs, upgraded to a Core 2 Duo CPU, that runs BunsenLabs Linux (based on Jessie and a 3.x kernel) just fine. In fact, it's one of the few Linux distros that still supports that 11 year old machine, long after even Apple left it behind.