Time flies. I hadn’t realized I was so far behind on updates (3.25 years!). I had originally held back on updating because I heard about softraid changes coming down the pipe in 4.7 however these have long pasted and turned out to not be an issue. It’s a testament to OpenBSD that it just kept work all this time.
For the actually upgrade I started with http://openbsd.org/faq/upgrade47.html and just continued until I reached 5.1. I used the Upgrading without install kernel method because I don’t have a monitor and keyboard hooked up.
After that just follow the instructions as necessary. I didn’t rebuild my raid array and dnsmasq and samba didn’t work out of the box but other then that suprisely pain free for a 3 year set of updates!