ALWAYS run a scan of the drive BEFORE you start dumping data on it. I use HDTUNE to scan any drive I buy for errors. It's free and the pro version has a 30 day free trial.
Also, if you buy a WD drive, you can use their in house WD Diagnostics to scan the drive.
It takes a long ass time to scan big ass drives, but I guarantee you that most people who gave certain drives bad reviews didn't scan them for errors prior to using them.
Portable simply refers to the fact that it draws all the power it needs from the USB port. Moving any disc while it's spinning could damage it no matter the brand.
If you can't afford two similar drives (1 for storage and 1 as a backup), imo you shouldn't buy large capacity drives.