My experience with powerline is pretty terrible. And there is no better place for it sadly.

I have a PC in a spot of my house I can't get a cable to. But that's the PC I do my Blu Ray ripping and encoding on, so I keep a 5tb external drive for moving the files to my NAS afterwards. Sometimes it would take days over WiFi instead of minutes to hours over USB 3 twice. (and piss off my wife for saturating the wifi, heh)

Hard drives are fine. But replacing them every few years for fear of failure is a waste of money. Drives can last over 10 years, or 1 day. Just have more than one copy and you'll be fine when one does fail.

/audio

It contains all my music and audio dramas (star wars, hhgttg, big finish stuff, graphic audio stuff).

My music, photos, and documents are backed up remotely (Dropbox).

Everything else is just backed up to another machine.

For me it's cost. 80tb wouldn't be cheap enough for me.