zamfir, i liked the ride with the kona p2 (a-c 410, i checked) more, than what i felt with a chris kelly that came with 420mm a-c. much more yo-feeling with the shorter forks. it's a question of personal taste, a little voodoo and whatever. i'm not sure if i could check the difference in a blindfolded test, if this would be an option in this sport.
if if talk about an 80mm sus fork, i think they suggest something that is more around 420 than 410mm. you could level it by choosing a higher building tire for the front.
i think this 410mm tb p2 forks of around 1995 were the best kona ever made. the longer ones from later years i've seen were not my cup of tea. they were different in butting, the dropouts looked cheaper and even the diameter of the tubes was bigger. weight was always in direction of 1000g and more for the later ones.
cheers
:sneb