I book most my flights with points, and hold a CC. So Basic fares are not much different from the old WGA fares as I rarely have more than one bag. I have rebooked several flights into basic fares at a decent savings(This weeks CUN flight is over 50% less than my previously booked tickets).

I don't do same day changes often, as my schedule doesn't change much. But that would be a reason not to swap.