It matters, sometimes a lot. I've had a few going 24/7 fail here. You can help them live by putting things like /tmp into a ramdisk, or telling various logs to be less verbose and so on, but they
eventually die anyway...I've had much better luck with an external disk drive on a USB<>Sata cable - even if it was one of those "bad" seagate laptop magnetic drives...just sayin.
But you can't always do that. There are now extra cost (!) SD cards that are based on MLC - one tech generation back! - instead of TLC flash, and some are pretty good.
See the chart, made by Chris at Explaining computers.
If you don't want to watch the whole video...
I can confirm at least that the faster ones do produce better performance on a pi3b and up. That A1 application rating does make a difference. As to long term, well, the sandisk model mentioned in the chart should be arriving today - but obviously I can't say anything about how long it will last. Since it's also just plain faster, it should be quick to slap an image on one, though, and see if it's as quick as the A rated ones (benchmark says it should be real close).
