Okay, I have symlinked it over, and now I'll run it like this for a few days to see if there's any bothersome effects.

I have some few percent free space now, but /usr is still a bit on the large size. It reports as 300MB and that on a 256MiB partition.
Half that in /usr/lib, another 82MB in /usr/share. I should go in there, hunting.