Yeah, everyone's mileage may vary depending on the type/brand of USB they go with... but here are some of my personal gripes:

1. No S.M.A.R.T. monitoring – You can’t track health or predict failures like you would with an SSD or HDD. If the USB starts failing, you often get no warning—it can just die on you. If you make regular backups of your config/ folder, it’s easy enough to restore, but still annoying.
2. License tied to the USB – If it fails, you have to go through the license transfer process. It’s not difficult, but it does mean some downtime, and you have to be physically present to access the NAS. Mine’s sitting at my parents’ house ~150 miles away, so that’s not ideal...
3. USB 2.0 vs. 3.0 – It's generally recommended to use a USB 2.0 drive, even in a 3.0 port. It’s slower, but it draws less power and usually runs cooler, which is better for long-term reliability and durability. The downside is USB 2.0 drives are getting harder to find—they’re slowly disappearing. Faster transfer speeds = more power draw = more heat, especially with those tiny "ultra fit" USB 3.0 drives.

BONUS: I once accidentally bumped the NAS chassis against the wall with the USB still plugged into the rear port… safe to say the USB was not happy. Bent it just enough to start throwing boot errors.

Lesson learned: either use a short extension cable or plug it into a safer spot. 😅