Sorry - crossed purposes somewhere. I was advocating Vref at 50ft because that is how the book says the aircraft should be flown and how the figures are derived. What Boeing, Airbus et all reccomend before you get to 50ft is whatever the company or manufacturer consider to be safe.
My point was that on a limiting runway 50ft at Vref is whats required to make book, up until that point then Vref +** is determined by whatever portion of h/w/ or gusts or other weather math you/your company choose to deploy
Framer is instructed to be at the Threshold at 50ft at Vref +5 hence my amateurish maths.
Sorry for mixup