It's a good fare, but a quick search shows me that Louisville to MCo is $59!
How many tickets are you buying?
If 2, that's only a savings of $40 - probably not enough to pay for the gas, nevermind the lost time. Weigh the plusses and minuses! Maybe in Louisville, you have family that will help transport and you don't have to pay airport parking, of course, gas to go to Nashville, then there's also any possible lost time from work for the longer commute to the airport.
We usually travel as 3, (me, DH, and DD) and flights have to be $50/each or more cheaper for us to even consider a different airport - and we have 4 within 2.5 hours of us!