Just came off the PTR, turns out the difficulty might've been significantly ramped up. And when I say HARD, I mean, in contrast to the difference between normal mode dungeons and Cata-release style heroics, not heroic raid HARD. I'd say the ilevel requirement would be the same as in the Throne of Thunder LFR: 480. 496 seems a bit steep when all you really need to do is avoid mechanics and deal with buffed-up adds.
Bonus objectives seem to mostly consist of vague timer runs, like, "Defeat BOSS X quickly" but with no mention of HOW quickly. This might just be a PTR placeholder, but if it isn't then you better hope the DBM team can data-mine timers or you'll be relying on randoms to pull off the appropriate DPS blindfolded. The "Avoid mechanics" objective reminds me of Will of the Emperor awarding bonus damage based on whether you can get out of things.