Both sims have the ability to enter your stats directly, and manually edit what set bonuses you have. So even if the import features don't work, you can still do your own work.
I'm actually in a dilemma right in regards to running the double 2p bonus for t12 and t13. My main issue is that I have a) the LFR tier and b) its the helm and gloves. I would be replacing heroic tier 12 in both slots, and I have to wonder if the loss of raw stats and ratings would be made up for in t13 2p bonus. It would be a no brainer if it was regular t13 or even the LFR versions of the shoulders and chest due to the extra sockets.
I've ran it through the sims in both simcraft and Enhsim, but apparently simming LFR gear is equivalent to dividing by zero.
On a unrelated note, I was able to pick up Heroic Vial of Shadows tonight, and the boost is pretty substantial. It scales on a straight 1 to 1 attack power ratio, is able to crit and the heroic version starts at a higher base damage. Heroic Vial coupled with my Wrath of Unchaining is just silly damage, and I am fully confident saying that the pair is BiS.