I was Linux-exclusive for a little over a year, I think? But I was also doing nearly no graphic design at that time, and when I went back to trying to do more of that, it became really hard not to use Windows because of Photoshop (I did get it to run on Linux, but it was too buggy to use). Also for some reason, internet would randomly not work, which was a little annoying. I did play my particular flavor of gaming on Linux-- I actually found it tended to run better on it at the time. (I play Guild Wars.)

But even though Linux is currently "dual boot" on my computer, I keep booting into Windows these days because of program compatibility issues like that, so yeah, I also understand not counting "dual boot" users. I'd really like to get off Windows entirely (at home, anyway, I know that's a pipedream at work, for sure), but haven't been able to as of yet. I may end up moving in the Mac direction, since, as kareila was saying, it's a bit easier to be Mac-exclusive than Linux-exclusive.