Requesting opinions and experiences replacing an old MBL single bay 2TB NAS

WD Legacy Products My Book Live
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I’ve been using the subject device for probably 9+ years now and it’s currently completing only 90% of both long and short diagnostic tests (death may be imminent). Even so, it’s still completing the daily Safepoint creation, which goes to another LAN drive (LaCie 2TB).
My inclination is to replace the WD MBL with another 2TB NAS - even after all this time I’m only consuming 460GB of mostly photos and music, plus some documents - but of course the extra cost to go higher than 2TB is negligible, so that’s another consideration depending on price.
Is the main advantage of staying in the WD family that I can transfer my Safepoint backups to the new device and continue with WD Smartware backups as if nothing has happened? How would I execute the file transfers so that this capability (if it exists) will be transparent?
Another option may be to continue with the old MBL enclosure and just transplant a new HDD (probably not optimal in light of newer available technology).
The main consideration at present is performance and usability. I’ve found the MBL to be painfully slow and cantankerous in terms of user functionality.
I’m looking forward to some great ideas and suggestions. Until then I’ll be taking an image copy of ‘old unfaithful’ and preparing to retire the old girl.
Thanks in advance.