If you revert to the stock setting of 3 turns, and you get better off idle performance, will you use that performance, or will you modulate your right foot to get only the performance that you need?

This is the problem with comparing fuel economy between the various ALDA settings. If you drive with your foot mashed, you will, of course, get better fuel economy with each incremental reduction in the ALDA setting.

The only fair comparison (and this is admittedly difficult) is to drive the vehicle exactly the same way, with identical acceleration, under different ALDA settings. I seriously doubt that most people can do it. If the power is available off idle, they are going to use it.