Long time ago I maintained a couple of obsd servers, and the cost in time of upgrades and the (occasional) security fixes was substantial.
I still maintain a couple of servers, but if it wasn't because Debian makes it easier by automating most of it, I don't think I could do it.
Yet I miss my time with obsd. I'm very interested in your experience.
Edit: it was 3.6-STABLE. Things have changed since then.