I can tell you my experience as to why Linux won out in production. Many years ago when I was doing enterprise systems administration, we were using both Linux and BSD equally in the beginning. But what eventually gave Linux the edge was hardware support and package management. Linux had solid SMP support first, which meant we could replace expensive UNIX servers like Suns and AlphaServers with much cheaper Intel based multi-processor servers. PLus Linux had more drivers for hardware like RAID and network cards. We didn't have to hunt down specific, often older, hardware like we did for our BSD servers. Also IBM ported Linux to it's z series servers so Linux had a (what we used to term) "big iron" server solution first and could replace proprietary solutions like the high end HP9000's. Package management was a huge plus. It greatly reduced administrative time. Major software upgrades, like when we had to replace libc6 on all our *NIX servers because of a major security bug, would take hours on the BSD servers but minutes on our Debian servers.