Here's a question for you framebuilders - is there any difference in ride, steering or anything else, between bikes that have the same trail but that have widely differing head angles (let's say 71 - 76 degrees)?
Maybe in your explanation you could use the two extremes of 71 and 76 degrees but with identical trail.
On an aside note, my last two custom mtb frames have had "unorthodox" 72 degree head angles. Of course I used available forks (so the trail couldn't be modfied by customized rake) and I couldn't be happier with the handling of my bikes. Where some (who have never ridden a 72 degree head angle mtb frame) would say "it gives 'quick' steering, I would say it gives perfect steering.