I am not convinced there are any/many issues with ULSD and lubricity. Lotta internet babble, including me I suppose, most of which is worth about what it costs. I haven't seen any recent testing done, like that '07 test. In those days, the application of the substitute additives was spotty but I have it on good authority that the current fuel is better than what it was when first introduced. Other than occasionally, because I got some free, I've not used a lubricity additive in the 6.9L since ULSD debuted. I may not be facing many problems because I put so few miles on the truck these days (got a new "main" truck in '08) but I'm willing to stand behind my assertion that there isn't much to worry about by letting it eat up my pump (if it's going to). As to why I put 2-stroke into my farm tank and not into the truck... pure laziness. It's easy on the farm tank. When I call to get it filled, I just add the stuff and it's there when I pump it into the tractors. I bought a bunch of it on sale but when I run out, unless I'm convinced in the meantime that a problem exists (I am ALWAYS willing to have my mind changed by good information), I will probably stop.
Cetane- It's long been known, and it showed up in the tests I did years ago on my 6.2L, that there are no gains to be had with a cetane rating above 50. IIRC, correct me if that's wrong as I didn't look it up, ours were designed for a CR of 45, so I doubt you would see any gains above that on an engine set up as bone stock. On my 6.2L I bumped the CR by 2-3 points until I reached 60 but the engine stopped gaining anything between 45 and 50. It gained a lot from 40-45 (the 9 hp I mentioned earlier). You used to be able to approximate the CR by using a specific gravity tester but that doesn't work any more on the new fuels. I think it's down to how good or bad the fuel might be in your area. I know the Shell distributor in my area and he tells me the fuel he sells is between 43 and 48 cetane. I have no reason to doubt him. I add Performance Formula here and I feel no gains. When I added Performance Formula to 40 CR fuel in Colorado, I could feel a kick. I was set to do some dyno testing locally on fuel but it fell thru. I'm more in line with the idea that CR are all over the map according to locale and may be low than I am about the lubricity additives