I installed it and used the venerable boot0 MBR boot manager. This is on an old P4. Repartitioned and reinstalled FreeBSD first. Took a couple hours to figure out OpenBSD partitioning and only clobbered the partition table once. It's installed with a half dozen packages and doesn't even take up a full Gigabyte. I did a 30GB,30GB,80GB split. So I can NetBSD or Dragonfly to try it later. Boot0 is nice because it remember your last selection and autoboots.
I did it mainly because I wanted to try OpenBSD again(been a few years) and play around with it's new firewall features. I have to say right off the bat it feels so much faster. Web pages just seem to come up faster. I need to run some real world tests and try to figure out why.