as per subject - free or paid version is fine. would like a proper diagnostic tool that works on traditional hard drives as well as on SSDs, and ideally one that allows a portable install so that I can use it on my desktop and laptop machines, and MAYBE even on my office machine.
if you have Seagate or Western digital hard drives, go to their respective manufacturer's website and download their diagnostic program. For WD it's called "Data Lifeguard Diagnostic for Windows" (other versions available). For Seagate it's called "SeaTools for Windows" (other versions available). Not sure if they provide anything for SSDs.
the "BUY NOW" link says 28Eur/$35US, so i paid $44Cad. it's close enough to today's exchange rate.
from what i learned by emailing them, the Pro (single license) can be done either as a install OR as a portable. the Family (5 license) can be done in any combination of install & portable (eg 1 install + 4 portable, or 3 install + 2 portable), which is kinda cool. evidently one can also upgrade from Pro to Family for just the approx price difference, which was good enough to get me to get the Pro for now.
initial scans of my installed hard drives indicate that both of my old Seagate 7200.11 drives are iffy - one is "ok for now" and the other is "yeah, you should start backing up and get a replacement soon". i figured i'd need to replace them anyways, but at least now i know more and know which drive should get priority.