I always thought it was the mass of the fuel per hour which gave all the relevant performance data (TSFC, Thrust etc) - so as long as you had the right number of kilograms on board you would make your planned range/reserve predictions.
Less dense fuel means you need more litres for the same fuel mass - something we always check (using actual, rather than standard SG) as part of pre-departure preparation.
I'm not a long-haul operator so am unaware of any situations where tanks were full (are they ever full in a B747 or A340?) but did not contain the required fuel weight.
Jet engine efficiencies depend on temperature change from intake
Yes, but surely the difference in engine efficiency between using fuel at 30C and using fuel at 0C would be negligible, considering the temperatures involved in combustion?
I have consistently flown longer, with more fuel remaining at the end of the trip, when I started with full tanks of less-dense fuel.
Maybe because AUW was significantly less than planned? (planned with 'heavier' fuel, that is) Again, I have little experience of operating at max range with full tanks (wouldn't be able to carry many pax!) so not sure how this is manifested in the bizjet world, which presumably is the thrust of the article.
How does the author of the second article account for in-flight cooling (to higher densities) of his fuel? Would that make a difference, according to that argument?