I read through the report and find some of it reasonable, with valid points, but question some of the others and believe they missed one point.
The missed point is not mentioning that the high-flow water pumps also require more power to drive.
One point I take exception with is their statement about cooling the Rolls-Royce Merlin engine. While true that the aircrafts fly in cooler air, the reduction in air pressure at altitude dramatically reduces the boiling temperature. Early R-R Merlin engines did not have pressurised cooling systems, but I believe that in the late '30s all were pressurised. Granted, the original '31 R-R may not have been pressurised, but there's no reason it couldn't have been pressurised when the R-R Merlin was installed.
It also appears No-Rosion was tested using water, only, which provides no freeze protection. I would have been more comfortable with the testing procedure if they had tested it in a 50/50 water-ethylene glycol mix.
One thing they are correct about is the volatility of ethylene glycol antifreeze. Several years ago there were a lot of motor home engine fires that were attributed to leaks in the cooling systems. Due to the high under-hood temperatures the water evaporated out of the coolant as soon as it entered air, leaving the straight ethylene glycol to combust.
These are my main points, but there are others of less concern.