Assuming that you have a manageable (realistically) mortgage to begin with in my opinion the decision comes down to whether or not you can earn more investing (withing your risk tolerance) than you can by paying down the mortgage.  Or perhaps a combination of the both if there are sufficient funds.

Assuming you have made at least a 25% down payment, pay weekly on an accelerated basis, and bump your payment periodically as your income increases I see little point in throwing additional surplus cash at the mortgage if you can earn more by investing.  When rates increase you can always make a switch to paying down the mortgage.