The ALDA only increases fuel for the off idle, low boost times. Such as starting at a stoplight.
If you increase the max boost it should not affect your crusing boost amount. It will help during merging, lane changing, passing, etc. It could increase your MPG as you can get up to speed, pass, etc quicker (You won't hold down the throttle as long.)
Anything over 12psi is just turned into heat unless you install an intercooler.