Jill, just wanted to say I'm sorry BB was such a hassle. I know a few people who've gotten an EHD from them with no problems...so hopefully this was a fluke and if you ever need one agin (knock on wood that you don't!), it will be a much smoother process.
Okay, that aside, to answer your purging question: I've started to think about my digi stash like my closet. If I'm not going to wear a 5yo dress because it doesn't fit my style (or my mom body lol), then why keep it? Same with old DS. If it's somethingt I'll never use, then what's the point of letting it take up space on my EHDs? The last time I bought an EHD (a beautiful 6TB by WD) and before adding anything to it, I opened up my second-most-recent EHD and deleted with no remorse. (But full disclosure: I have that stuff on at least 2 other EHDs*.) So as long as one of those works, I'm okay...but I don't care if any of those EHDs fails because everything I really care about (photos, more recent DS) is backed up via BB and on two other EHDs.
I've also decided that when I get another EHD (I'm currently down to only 3 with space; I like to have 4), I'm not going to add any DS older than 2019 onto it--and even then, I'm just going to quickly go through my laptop and drag/drop onto the EHD. It won't be a big process. I'll still add all my photos because I am ridiculous about backing up photos lol.
*Just a quick comment that if you have your DS product on
just one EHD (but not your computer) or on
just your computer, then you don't have it "backed up." BB is a great way to back up, but having a second physical copy is good, too. Here's an article from BB about the
3 2 1 Rule.