I don't think we should unduly bias the test group; say "an encyclopedia with no space limitations". They may /already/ think that Wikipedia is something /other/ than an Encyclopedia.
I'd be interested in hearing the answer from all the people contributing to this discussion.
Personally I think the only restriction is we should limit ourselves to articles on things (including concepts) other than words. The rest is just really realistic limitations on how to accomplish that. NPOV and verifiability are necessary because we're a wiki, and "no bots" is necessary because we generally need to be able to organize the information as we add it.
Other than that, I don't think there's anything we can't handle. I'd like to see us add the name, address, telephone number, and social security number of every person in the US, for instance.
Anthony