I don't believe the numbers will be even this year, for numerous reasons we have already gone over. I think it is legit to assume a 3-5% spread in favor of the Dems. But 10% is absurd.
Every action has an equal and opposite reaction. IMO, ACORN + large numbers of pro-Dem early voters + media effort to coronate BHO before the election = major increase in GOP and pro-McCain Dem turnout on election day. I wouldn't be shocked if turnout is equal or slightly pro-GOP.