LC does not save that much fuel (you're already not using much fuel at light load)... but even at light load, running lean will elevate combustion chamber temperature (which is not good for many reasons; remember, EPA/CARB likes the engine to run hot, but they don't like it from being lean).
( NOx might not seem like much, but if you've ever seen pictures of Los Angeles buried in brown fog in the late 1960's (I've also seen Sydney like this in the 1970's) then you know that NOx reacts with sunlight to make brown fog. )
( either way, LC is not really necessary, you're not saving much, and your engine does not really like LC )