Yep, would have told my son to not pay off a dime of his loan.
I paid off my loan in about nine months because I didn't want to have to bother making the payments every month. But that was when college was cheap and you could easily pay off college loans in a short period of time with a professional job. I've done a lot of study into asset bubbles and market crashes and the common issues is debt to fuel bubbles. I'm pretty sure that we engineer these bubbles on purpose and then pop them when we have no other choice.
Given that, I'm loathe to borrow money. We paid off our mortgage in 2000 and so were able to pay college expenses out of income and a little out of savings. Our savings rate was 38% between when we paid off our mortgage and when they started college.
Why would you want to encourage debt for your kids? I understand that that debt can have some benefits but right now, there are hedge funds blowing up due to leverage. And this stuff will eventually bring us to recession; along with the Federal Reserve QT and rate hikes.