Re-impressions: the manual is so nice! It really blows me away every time I look at it.
My first major hurdle was mounting my ext3 drives full of data. No matter what I tried, I'd find:
# mount -r -t ext2fs /dev/ad0s2 /mnt/a
ext2fs: /dev/ad0s2: Invalid argument
Or a similarly confusing error message. Some things suggested I compile in ext2fs into my kernel, so I tried that (FreeBSD kernel configuration: much simpler than Linux), but no luck.
Then I found it:
# file -s /dev/ad0s2
/dev/ad0s2: Linux rev 1.0 ext3 filesystem data (needs journal recovery)
I'm pretty sure I shut down Linux the last time properly, but who knows. I booted off the Debian installer CD, and after fighting with devfs paths, mananged to mount and unmount the drives, and now all is well in FreeBSD-land.
Now to figure out what sort of RAID setup I want.