Switching Bikes For Commute?

I am currently using a Trek 4900 Mountain bike, it has 24 gears (8*3), front suspension, 3'' wide tires with knobles and a road stripe (hybrid) and weighs roughly 30 pounds. I can do a 15 mile loop in an hour, easily. But most of my riding is on paved roads so a mountain bike seems unnecessary but I did inherit a 1980's or 90's Schwinn World Sport Road bike with 12 gears (6*2), no suspension and 1'' wide tires, it also weighs about 30 pounds. Would it be advantageous to restore (new tubes and pedals) the Schwinn? or stick to the newer mountain bike? and how much better would the Schwinn preform on roads compared to the Mountain bike?