First, check to make sure you have 40psi in both tires. The manual use to say 33psi, but it's wrong.
I have been using Dunlops since I bought my bike. Others have switched and say they like the ride better with the different brand. Ask around before you make any decesions.
And...............what is your style of riding? Long trips/short around town??
Do you ride hard, powering into turns etc?? I would say if your just "cruising" and leisure, Stock tires aka Dunlop tires are ok and you should get ok mileage out of them. Other wise like S/G said.