Allow dex modifier to increase attack speed and movement speed for all toons.
So at 40 dex, a toon would get +15% attack speed and movement speed.
This way toons heavily invested in dex will get a higher bonus while toons that go str can still get a slight boost (16 is easily achievable granting +3% attack speed and movement speed.)
This goes along well with the impression that a higher dex allows faster speeds in both attacking and movement.