... A steady right foot is better on fuel economy than cruise control...
Are you sure?
100%, both from experience and just a knowledge of how a cruise control's controller works. The cruise control won't keep a constant output, rather it will cycle around the value you set it to, so it will overshoot, drop back down, go up, overshoot, drop back down, etc. A bit like how a heater keeps its temperature. The time it spends bringing the speed back up will use more petrol. So instead of using a constant amount of petrol over time, you'll be accelerating occasionally which will inevitably use more petrol. The better the controller the closer it will be to using a steady right foot, but most of them are pretty basic.
If the word of someone who works with them isn't enough, remember the episode of top gear where Clarkson took an A8 to Scotland and back on one tank? He turned off cruise control after a while and commented on the increase in fuel efficiency.