No one can tell you that.
While you might qualify for a lower student loan payment, there are some tax deductions and credits that are reduced or disallowed when filing separately, including the child and dependent care credit, and the ability to contribute to certain retirement accounts. MFS almost always has higher tax rates overall, so you will probably pay more income tax even if you are not affected by the limits on credits and deductions.
Then, whether the higher taxes are worth the lower loan payments is a personal decision. You also need to factor in what happens at the end of the loan period. The rules keep changing, and I don't know what the law is right now, or what it will be in 10 years. For example, if you don't pay off the loan and it is forgiven, the forgiven balance might or might not be treated as taxable income in the year of forgiveness. Loan forgiveness programs might change with the new President, or loan forgiveness plans announced by the current President might be blocked by the courts. The risk is that you pay higher taxes for several years and then don't get the benefit of forgiveness to offset the taxes.
There are too many unknowns to give a one size fits all answer, you have to look at your situation and how MFS would personally affect you.
