they get progressively stiffer. i have the first years and they are awesome, basically a slightly stiffer, slightly narrower, and thus more versatile hellbent. i find them to be pretty much killer everwhere. float well, can push through some crud, still pretty stable at speed, and even do surprisingly well on groomers considering the dimensions. (mounted at 3 back from center btw, thats the recommended line)
this years are a bit stiffer in the 186, and a good bit stiffer in the 190. 186 is still ideal for pow jibbing, 190 is better for gnarlier lines and whatnot.
from what i understand next years will all be about like this years 190, but i havent ridden them. hope that helps.