Lubricity worries are overrated as our fuels systems a ULSD compliant. In fact the wear scar requirment has remained the same for years (lower is better and did not go up with move to ULSD).
All additives which contain a cetane booster contain 2EHN or Xylene, Napthalene, Ethylbenzene, etc.
Diesel combustion is already over 99 percent although quality varies with fuel characteristics and engine type. Additives may change the quality of the combustion but won't yield significant increases in power.
Diesel fuel is not the same from every supplier. Each batch responds differently to a booster. When I say respond I mean increase in cetane level. Fuel X may go up 6 proints while fuel Y may go only 3. Fuel X may start at 40 whereas fuel Y is at 45 but you don't know because federal law says 40 is min and pumps always state min.
Higher cetane works its magic at cold start for emissions reasons and it smooths out the engine (wont knock when cold). I suspect a cold start is where fuel is saved. At operating temps cetane does little other than at very high engine speeds (higher than what we normally drive at).