First of all after Perfect Aim goes down MG/DS don't proc CRIT dots.... one reason. and for second reasons I?m going to copy paste something what was posted on other forum so I don't have to rewrite someone elses findings.
"I think it goes back to where you have this scenario...
Unerring procs and you SB:SS your DoTs. Now they're critting 100% of the time. Then Wushoolay's is at an 8 stack, Tempus Repit procs, and Jade Spirit is live. Affdots reads 130 for Agony, UA, and Corruption indicating an increase in DoT power. Now you override your DoTs with a new SB:SS. All your procs fall off and Affdots reads something abysmal like 20. Now Unerring procs again....you'd have to choose to ignore it. Affliction DoTs don't benefit from Crit in the way Demo and Destro's do where they give you more resources or extra damage mechanics. They just do double damage. If you somehow got Unerring to line up with all those procs, hell yeah, you'd be golden. This happens at the beginning and then like 1/1,000,000 later in the fight. I just think Unerring provides too many complications for Affliction and isn't long enough to be truly beneficial for Destruction. Also remember that your mega DoTs are also capable of critting although at a less percentage, usually around 20% based on reforging. An empowered DoT crit > normal hit guaranteed proc. So the real umph from Unerring gets softened by the other snap-shotting capabilities of other trinkets, namely Wush and Breath."
Do some real tests with both combination of trinkets on real fights not dummy and you will see the RNG UVLS puts affliction on. empowered dots when you have Lightweave,Jade Spirit and Woosholay and or Meta gem are doing much more damage then just UVLS. Do the math, put it on paper, watch logs and you will see. UVLS is good ONLY if it procs in a good moment together with some other INT proc. If you think you know something that others don't please tell us so we can put it in Simcraft and we can do the math your way.
and btw you have approx 20% crit in raid, UVLS gives you 80% CRIT more, because Affliction doesn't benefit above 100% so it's not that much. Yes on pull you usually destroy the meter but rest of the fight is just plain lottery with 1/10000000 chance it will proc in a good time. God forbit it procs on phase where you are dpsing adds, or on iron quon on shield or something, pure dps loss.