Thank you for the link to the new poll! (Do you still have any saved numbers from the earlier one on lj, and if so would you be willing to share them?)

I wouldn't be surprised if the proportion if you included all the different communities that identify as slash was someone around an even split, or 60/40 either way. I haven't found any of the the heavily-het corners of slash fandom yet, but they're probably out there somewhere. Maybe.