I stick to one table and I doubt that that will ever change.
-Paying attention to other players helps with reading. I don't think you can ever have too much information on your opponents.
-If your focus is not entirely on one table, then I think it's possible to miss many
bluff opportunities.
-If you DO have the ability to focus on more than one table, then I think you could capitalize on that by playing on one table and watching other tables in the same tourney. That way you only have to worry about playing in one, but you can still get information on your opponents that will be a nice advantage when tables are closed off.
-Personally, I've tried playing on two tables at once and have found that my play style becomes sort of auto-pilotish which is easy for others to take advantage of.