Good arguments on both sides. Here's how I'd break it down:
1. 4.8% is boderline when it comes to guaranteed return by paying debt, and taking the risk for greater reward in stock market.
2. Is it fixed or variable? If fixed, see #3. If variable, that rate WILL go up. Start paying it down now.
3. Is your retirement target longer than 10 years away? Over 10 years, you have a very good chance of earning more than 4.8% in the market. At least 1-2% more annually, after inflation, possibly quite a bit more.
The bulk of my own debt is at 6.5%, so I'm throwing everything extra at that. If mine were at below 5%, though, I'd be paying at the normal schedule, maxing my Roth, and then building my taxable portfolio since my target retirement date is 15 years away.