Further reading of the ThinkWiki led to this page which details installing Feisty onto a T60. While the hardware isn’t exactly the same, the symptoms described on that page (especially with regards to problems with suspend to RAM) sounded familiar, so I tried their suggested fixes, which seem to work.
So now my X60 suspends and resumes pretty reliably. But issues remain.
Joining a WEP-based wifi network seems to take forever, and sometimes just never works at all. I’ve also seen instances where the network manager seems to forget that I have a wired ethernet card (which is always detected correctly on startup).
The last little bit I’d want to work before I could switch was the hard drive shock protection system. To my surprise, it looks like a lot of code has already been written for it. ThinkWiki has this page about it.
Unfortunately, while Feisty seems to come with the required kernel module, none of the userland utilities worked. They have a fancy gl-based utility that graphically shows the tilt of your laptop, which showed nothing, as well as a command line utility that continually prints readouts from the accelerometer, which also produced no useful output.