i tried,but sims have been giving weird results, haste is the best stats for me according to sim, despite that my mastery is at 115% and haste at 21% so I'm not sure if I can trust it. the legendary simd better at 20k dps tho
Helm is probably best. My simplistic way of thinking about it is: 2pc = 10% extra total UA damage. Legendary Helm = roughly 10% more UA, and 50 ilevels of gear.
4pc vs legendary helm on the other hand seems harder to determine.