Based on the old testing thread buried somewhere on the forums, +2 WIS provides an increase of 3.125% shots (and thus DPS) in 10KStars. However you need to half that since 10KStars is only up half the time.
The +1 Crit multiplier on a 19-20/X3 crit profile bow yields an increase of about 8.7% DPS.
Going Water over Earth would only yield an increase in DPS if in Shiradi.