NetBSD day one
So I decided to experiment with NetBSD (i386, the 'stable' 3.1 version). So far... eh. Not that impressed, especially since I encountered two issues just trying to get it installed and bootable:
1. NetBSD will rewrite your MBR ! It does this even if you create a NetBSD partition using, for example, Linux fdisk. In my case, the damage appears to be limited to a pointless change to the disk geometry, that nonetheless causes fdisk to get quite upset: the geometry was changed from 255h 63s 7297c to 16h 63s 116301c. This change causes fdisk to complain about partitions not ending on a cylinder boundary. It is easily enough repaired from cfdisk (fdisk wouldn't do it for some reason, but cfdisk would) using 'g' to fix the geometry (I changed heads from 16 to 255, and it figured out the cylinder change for me, which was comforting). Another symptom of this was that in sysinst, after partitioning, the displayed MBR changes had wildly different start/end cylinder numbers.
I don't know if I just got lucky, or if this 'repair' will always work, but I'm kicking myself for not backing up my MBR! The takeaway here is: if you already have a partition set up for NetBSD, be sure to back up your MBR, since sysinst will change it even if there's no reason for it to do so.
2. NetBSD doesn't boot properly with GRUB. This turns out to be (sort of) documented, other than the sample grub.conf I got from Gentoo (probably stock from the GRUB tarball) used the "kernel --type=NetBSD /netbsd" method to boot. Which will work, except that because GRUB doesn't/can't pass kernel parameters to NetBSD, you will get prompted for the root=, dump= and init= parameters. Using the "chainload +1" method to boot NetBSD to avoid this. Which is a little annoying, since I had previously used (and preferred) Lilo, the only reason I changed to GRUB was because it supposedly could boot NetBSD directly. Now that I see it can't, I'll probably switch back.