Okay, so after a week of testing it out, I have noticed a couple things: (I have triple kriderShot)

Lightning needs to fire Elelemental arrow ALOT. With Meticulous bolts (30 something % slower ball lightning) You generate ALOT of hatred but you need a ton of the bolts out there to keep up damage.

Stuns are OP. With Custom Engineering it seems like anytime I have three sentries down (elites, champs and bosses) they stay stunned forever. Add in the fact that I am using Strongarms and dmg is insane.

I have changed my play slightly for normal (T6) rifts. I bait enemies back to a sentry filled spot. I pretty much put 3 sentries down somewhere and kite groups back and laugh as they get slaughtered. This is not by any means required, its just a lot of fun.

GRifts are the same I am still clearing lvl 36-38 rifts and just missing the timer on 39+. I think this is a product of my skills more than that of the build.

Overall the synergy is good. I think that the dmg output by lightning is the same as that put out by fire/frost you just don't see the big numbers. I can clear Grifts lvl 32 solo on all three. The synergy is what allows me to get up past 35.

Overall grades:

A+ for Normal rifting (mainly because of the sentry ambush)
A for Grifts (like I said probably me)
A for Everything else. Bounties are stupid easy when boxing, Grom is a joke. Greed same. Whimsyshire is too easy.

If my brother-in-law wasn't playing the game I think I would add in a fourth Phys DH just for another strongarms buff. He runs a Monk and lets face it, they should be in every group. (I think he likes the free loot)