Hobo. Can you quote an authoritive source on this 80 knot thingy for Boeing? I find it a bit difficult to accept that Boeing would nominate a 80 knot call purely based on a 1943 vintage aircraft. My bet is that someone has heard this from someone in the industry and it gets passed down through history until it becomes "fact". Blacksheeps point about 60 knots being the lowest ASI reading before the needle comes off the stops sounds a more valid point of view.
In large tailwheel bombers - and I flew Lincolns - a slight forward pressure was kept on the wheel until the tail gradually came up. It was never done at any specific speed. One thing though about the Airbus 100 knot check and that is it sure removes any decision making about going or aborting if an ASI discrepancy is discovered at that point. It is go man - go!