Well, really since a QFR in greens can be had for about $20 more than the blue version, if springs are cheap, i'll convert it, if not i would just sell and buy a green board.
( or buy a cheap black board and convert the blues to greens and the blacks to reds )
I did try to find a spring off a clicky pen that would work so i could see what a heavier spring would feel like in a blue but couldn't find one that fit.