how much interest is the loan that you could pay off now? If its that 6%+ one, you will probably get a better "return" on your money by paying it off now instead of letting interest accrue for 5+ years.
Personally, I wouldn't be super interested in the SL payoff assistance after x years of working. I would want the freedom to change employers every few years and not feel stuck with a company because of the SL thing. You might actually come out better off moving companies and getting those big raises and using the raises (no lifestyle inflation!!) to pay them off. I would likely use the signing bonuses to knock out a big chunk of the SLs, but I'm kinda meh about the SL payoff perk.
If you stay at one company, you can expect regular inflation raises every year and maybe a few promotions, to the tune of maybe 3-4% raises every year if you're lucky. However, my DH has changed jobs twice within 5 years and each time got a 30%+ raise. He has more than doubled his salary by changing companies. Those raises compounded over time are MUCH more valuable than the amount we have tied up in our SL debt. And we have a lot more than you :) With those raises we are easily paying off the $80k we still have left AND saving significant amounts in investments.
However, that advice is dependent on your career field. Are you in the tech sector? That's where we are and it is super easy to move jobs and no one bats an eye. If you are in a more traditional field, moving and getting huge raises like that may not be as common. Without more information I can't give better advice.