I would need to look into how much spellhit you need to have 100% chance of hitting spells vs 0 NR targets. Would be tempting to go to 100%.
I've been told repeatedly that there's always a 1% chance you'll see a resist on someone your level, no matter what you do.
Why not 5/5 Flurry and 2/3 imp. LS?
I get about 14 extra damage out of Lightning Shield per proc by putting that talent point into improved Lightning Shield. Lightning Shield procs maybe 3-8 times in a normal fight, so that's roughly 40-100 extra damage per fight from the investment. I can boost the damage with various trinkets, too.
If I instead invested that point into flurry, that's a 5% attack speed boost for 14 seconds for the next 3 swings after a melee crit. The chance of this single talent in flurry actually resulting in an extra hit that I otherwise would not have landed is rather low, especially with my tiny 19% melee crit chance. In the case I do land an extra hit, I'd probably get around 300-500 damage from the investment.
I don't know how one would go about finding out which is actually better, so I picked the weak-but-dependable investment. I don't think it really matters though, either way the investment is hardly detectable.