I have used actual lean cruise in TBI ECMs, TPI ECMs and the EBL as well as with the 0411. I have also used open loop pseudo lean cruise calibrations in vehicles that did not support lean cruise like my Hemi Ram. I have found that well tuned lean cruise will often return 10-15% better fuel economy at steady cruising speeds than without. That is running 16-16.5:1 air/fuel ratio with a bump in timing as the slower burn of the lean mixture can often result in the need of 4* or more timing added. Furthermore running on the lean side of stoichiometric will actually drop EGTs. A good example of this can be found in most aircraft pilots manuals with information on setting cruising air/fuel mixture. Most information out there has a pilot adjust to find peak EGT (which is at stoichiometric) and then further lean it 25-100*F. On an air cooled airplane substantial reduction in cylinder head temperature is also noticeable.

For example one such study can be found here.
https://docs.lib.purdue.edu/cgi/view...xt=techdirproj