Thanks man, and for that Canon 85 I'd have to say the non-DS for me but that's all down to the 1.3 stops of light you lose when wide open basically making it a F2 in terms of low light photography. And since I shoot manually almost all the time it would really throw me off since each 1/3 of a stop click from f1.2-3.2 wouldn't correspond to one for the shutter speed or ISO. A live histogram like you can have with a mirrorless body would help to offset this but that is one more thing to keep track of instead of your subject.
Watching that video I'm also wondering how specialized an effect this is. If you shoot a lot of photos with lights behind someone like their main comparisons the DS would be the way to go. The only other direct comparison shot is around 40 seconds in but here it has bright white flours which while not as intense can still be a decent light source compared to the rest of the scene. I really wish they would have done the scene at 4:19 with both lenses so you could see how they each render other types of scenes. With that big of an unknown I gotta give the cop out answer of saying that if I didn't have the issues with the light loss and was torn between the 2 I'd have to rent both and to see how they complemented my work.