Mr. Hoppy,
I don't have the statistical data to make the case for or against flex. I did just read however , that statisticaly, you have about the same chance of losing a tire as you do an engine..
If I was lining up on a 7000 ft field, I would much rather lose that tire on a 4000ft take off run then on 6000 ft take of run. More time to deal with it.
Longer runs, just like longer braking distances heat up the tires more. Also longer runs tend to pick up more goodies on the runway, such as parts from other planes, the result I am sure we can all sadly remember.
exactly how do you:
a) Identify a tyre burst?
b) Calculate your new stopping distance?
You may also like to check out the manufacturers recommendations with regard to high speed stops!