Mike kept getting combustion gasses in the coolant - I know this from his long history of troubles with his 1.9td. Now - I tried to argue Evans for him(EDIT: he has so far not used it), given the high altitude and tendency for normal coolant to hot-spot - so my theory was that Evans would allow even-heating across the whole head, even under extra hot/high stress conditions - so it may be that not running Evans would make for more distortion of the head and more susceptiblity to the "defect" of the new version of the headgaskets.
I guess keep an eye open for gasses in your coolant, is the point to be making. I hope you don't find any