The numbers need to be considered, but this is probably one of those lifestyle/comfort choices more than a math decision.
Worst case: Mortgages and student loans are treated differently under new bankruptcy laws than other debt. The student loan balance won't go away if you run into unforeseen financial trouble.
Best case: Letting 3.5% ride while making smart savings, investment and house-buying choices could look really smart *if* the math and luck goes well.
I didn't have student debt, but at 30 years of age I had $20k credit card debt, $10k auto loan debt and $60k in a 401(k). The debt was becoming a burden, and I wanted out of it, but due to early withdrawal penalties and taxes, using the 401(k) funds to pay off my debts would have wiped out the 401(k), and then I wouldn't be sure if I had the discipline to avoid running up consumer debt again.
So instead I set out to pay off the debt and was able to speed it up by selling the car to cover the loan, buy a cheaper car under better terms, consolidate my CC debt on a relative's lower-interest card and then pay off the debt over 5 years. During the paydown I still contributed to my 401(k) and had about $1k in cash cushion, but had no "emergency fund" outside of available credit or retirement savings.
At that point I still had my retirement savings intact, was debt-free and knew I could maintain a budget to avoid running up more debt. After being tax-free I was able to build after-tax savings and buy my first house. Somewhere in there I bought and paid off another car. My next car will still have a loan, but I think the one after that may be bought in cash.
So from that angle my leaning is to prioritize paying off the student loan, but I can certainly see the appeal of letting the 3.5% ride while making other smart financial moves.