I have tried desperately to find this game for a few years now. I am left with the impression that it is incredibly rare, today.
So the idea you can't use an ENWorld poll, especially if it hits 1,000 respondents, or randomly poll 1,000 of the 30,000+ GenCon attendees, and get good data is seriously erroneous. If you want to make it even more solid ask demographics. Age group, income group, racial group, sex, etc...
You have the basics of it. A "sample" is just that. A sample. You NEVER interview the entire population. This is why polling surveys are so popular. It allows you to question a very small portion of the population and derive accurate information that can be generalized to the over all population.
Keefe summarises my original point quite succinctly: EN World and GenCon attendees, in my opinion, are not representative of the general population of gamers.*Yes, you´re mistaken. What you need is a sample that is representative of the whole gamer population. A minority is indeed enough to generalize from when that minority is comparable to the majority in diversity and composition.
So, if you poll ENworld, you can generalize stuff about hard-core D&D DMs and players that post on the internet. Not the D&D gamer population as a whole.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.