My BX750MI-GR has saved my precious data on two occasions. Earlier this year, my seven year old, well used waffle iron shorted, popping loudly and sparking quite brightly in the process, probably because of all the gunk that had accumulated inside its less cleanable interior over the years. That not only made my breaker trip, but also blew the 16 amp main fuse. The UPS kicked in immediately, making a klick and a beep, which felt amazing. That was my first time ever.
As for the second time, see this post.
I have an old one. The battery is dead, I could replace it, but I didn’t really see the value. Power going out isn’t a terrible thing in my view, it happens so rarely for me. It’s a time to reflect and choose simpler activities.
The habit of saving early and saving often is so ingrained, I’d not lose more than a few minutes of effort on whatever I might be doing at the time that’s mildly important to me.
Mad respect.