Not sure about the memory card lifetime, but it saved my Pi 1 Model B from the long transition from "why did I buy this" to "I might as well trash this, it's too slow".

Found it last year in a drawer and couldn't get anything modern working on it. A friend mentioned DietPi when I was complaining about it and now its been powering AdGuard for my entire apartment ever since. I run heavier things like Home Assistant and Plex on beefier setups, but it's nice finally finding a use for it after all these years

It's been running it on a Pi3 for my garage door controller for well over 3 years (probably closer to 4 now) and I don't think I've logged into it more than once since I set it up. Really no complaints here.

I have been running it on a couple PI Zero W’s for three years running nodejs controlling LEDs. Probably not too write heavy, but no issues.

I don't have baseline for comparison - running HomeAssistant for a few months on RPi 4b, currently 34 days uptime and no issues in sight, htop processes list fits in half of the page. Can't comment on SD card lifetime because I'm booting off SSD - I actually haven't had SD card die ever before... Probably luck

DietPi creates a RAM disk for storing logs to reduce SD card writes.