I'm talking specifically about a graphical operating system for desktop purposes, something that people coming from Mac OS 9 or Windows 98/ME might have moved to. I think BeOS was far closer to providing that than Linux was in 2001, and that that might have mattered if it'd had been picked up and developed further as opposed to dying on the vine. I think there were a lot of people who looked into desktop Linux at that time but didn't take to it. A freed BeOS would have had a much better day-to-day alternative than Linux was, and running on cheap hardware unlike Mac OS X.

I don't really think your idea of A/B testing commercial vs. open source holds water. Look at what happened to OS X vs. Windows during the 00's, there's no comparison. There are so many other things at play.