I grabbed a sports radar this spring and have been very disappointed to find that flex has very little effect on the speed of my shot until it drops off from being too whippy. From 110 down to 85, it really seems to be hand speed more than anything else. The release feels very different, and my Ribcor Pro3 (85 flex, P02 curve) fires harder than any other by a few MPHs on a clapper, but overall the speed is the same. I was really hoping to see bigger differences considering how much time I've spent worrying about flex. So between 87 and 82, just go with what feels better. The actual effect on your shot is likely minimal.
For reference, wristers come in at roughly 60-65 mph. No skates, with a shooting pad. So Im not exactly an expert on getting the most out of stick.