This presents an interesting breakdown. Now obviously EN World isn't entirely representative of the 4ed gaming populace, but it isn't entirely unrepresentative either. How so? Because EN World is comprised mainly of serious to hardcore gamers and serious to hardcore gamers spend a lot of money on books (whereas casual D&D players will only buy the PHB and one or two other books, like one of the Power books or PHB 2).
I'm wondering if Wizards of the Coast has done any of this sort of research and if not, why not? I mean, couldn't they do a poll like this and then look at the results for, say, the Player's Strategy Guide, and rethink their decision to pour resources into a project that will net less profit?
It is also interesting to note that the percentage numbers for the various series' tend to go down (i.e. Martial Power sold more than Arcane Power which sold more than Divine Power which sold more than Primal Power which will presumably sell more than MP 2; now this may have something to do with passing time, or it may be that less and less folks are buying "splats" due to D&DI).
Keep 'em coming, folks. I only get paid by WotC if I get 200+ responses.
JUST KIDDING!