Panasonic Toughbook CF-29: Worked fine, though the last time I used that machine was back
in 2015, so can't say anything about recent kernels.
There were a few kernel versions where the machine refused to hibernate - basically, after
2-5 seconds of trying to hibernate it gave up and resumed normal operation - but overall,
it worked fine.
Thinkpad X220: usually works fine. I haven't kept a track of any kind, but generally
the issues I had were one of two types:
- Ridiculously long time to hibernate. Once I actually noted the hour when I pressed
"hibernate" on the keyboard and compared it to when the machine powered off -
and it was an astonishing 8 minutes.
- Similarly to the point above - long time to awake. This always took the form of the
kernel loading the image just fine (and with normal speed), X11 showing up on my screen...
and it's all frozen. The system could then take anywhere from 2 seconds to 4 minutes
until finally - for lack of a more accurate description - the userspace woke up, and then
everything continued working normally as if nothing happened.