Alternatively, one might perhaps be better served going back to the pub in such conditions and toasting the brave folk who took off ?
Well. that's always the best solution, no doubts. I'm not against that extra 20 Kts at all I'm just trying to comprehend how it's supposed to work in reality. I've never seen it or heard of it before.
If conditions are such that one can't conduct an overspeed takeoff with even a remote degree of safety, then what permits the safe conduct of an on min speed takeoff under the same conditions ?
Well, the answer is simple- dynamic of the situation and knowledge of local particularites. NRT for instance can have severe LVL WS on a clear sunny day with anticyclone weather. It's on the ATIS with announced +- 20 Kts speed gain and drop most of the time associated with cross winds and yet the show goes on. So it all depends on when it hits you with what magnitude. Aviation had to be seized in the far east for at least 3 months following the beer is better than WS philosophy yet it goes on.
P.S. I should probably clarify the reasons of being perplexed. While airbus is basing it's entire philosophy on the concept of energy installing sophisticating tools to keep that min level of enegry recognizing the fact that IAS is meaningless in case of WS with the range of total 40 Kts. Boeing solved the problem of kinetic energy by adding 20 Kts to VR. When VR+20 is indicated and rotation is inititated and in the very next instant it's -40 Kts where does it leave one?