Finding the value of Elemental T17 4-Piece

[Uthedicia 3]

So, I'm looking over the elemental set bonuses and I think everyone will agree with me that two piece is well worth the price of admission. No math needed. What the more complicated issue for me is if the four piece is worth taking 380+ mastery and roughly 200 in either critical strike or haste? Haste and critical strike are great depending on what you want to do but mastery on these items is a bit frustrating. 

 

Would having a lava burst be available every 12+ stacks of Fulmination outweigh having the lava bursts you can already obtain multistrike or cast faster? I'd answer this question myself but I REALLY wouldn't know where to even begin. Any mathematical calculations you can show would also go a long way toward teaching me the finer intricacies of "numbercrafting" these concepts. I appreciate any assistance or redirection on this inquiry. 

[Torch 0]

This might be a really basic way of looking at it but i have a spreadsheet of DPS increases as you gain set bonuses.

 

Might help you but here is the result for Shaman's ..

 

[Uthedicia 3]

Thank you for the reply. It appears to be about a 0.89% increase in DPS up from just having the two set. If I claim this 4 set bonus, I'll be claiming it dead last. 

[Cheze 6]

You would compare damage from LvBs gained over the course of the encounter with the 4p (minus that many GCDs worth of filler) against the overall DPS lost by having slightly-less-than-ideal stats.  I can't claim to have run the numbers myself but I doubt dropping the 4p is worthwhile considering that three pieces (hat/shoulder/hands) are quite well itemized and the difference between the fourth (chest) and the best alternative (siegemaker chestguard from blackhand) is not that large.