As I've said since way before the expansion hit, MM was going to wipe the floor with BM in Mythic+, especially the higher affixes, with any kind of competent hunter. I've been running with BM hunters in Mythic+ who have legendaries and better gear, and it hasn't even been a competition. They have to switch to MM if they want to compete. I've offered to run with others, given out my bnet handle, and I've had a few takers. I have never lost to a BM hunter, especially not on big trash packs. I have guaranteed MarkS procs on pull, and even if I don't, it comes up pretty frequently. Stampede is only reasonable burst if the entire pack stays at the center of the line pet pathing for the entire duration, and that's pretty rare, especially with large packs and how they jostle for position around the tank. The argument that BM 13 traits is any way equivalent, much less better, than MM 20 traits is based on sustained AoE sims (not in game performance), which as I've been saying for months is not the case in Mythic+.
SW/MarkS is way too much burst, and Barrage is just icing on the cake. If you go Crows, you're still going to beat BM hunters if they blow Stamp and you blow TS. Further, BM hunters have been pulling more shit with Stampede than I ever did with SW or Barrage, and it's usage means the tank cannot move adds for the duration (this is actually a problem with the Sanguine affix American servers have this week, if an add dies and drops a puddle during your Stampede call). Mostly because playing BM makes you pretty lazy at learning the instances before you go into Mythic+. This pervasive argument from people on this forum that "MM hunters are idiots" is just an extension of the "hunters are idiots" meme that has been around since Vanilla. If you're running with an idiot, it doesn't matter what spec or even what class he is playing. He's going to pull the whole damned room because he's an idiot. And if a MM hunter is telling you to move away from the drakes in HoV or away from the birds in Maw, then as a tank, listen and do your job because they're probably trying to help the group and not just make your job harder. That MM hunter is going to be worth his weight in gold in terms of dps, especially in add packs, if you can just learn how to use him well. And if you want to do Mythic 8-10, then you should understand the capabilities of your group.
MM forces you to completely learn the instance. If you played MM through heroic dungeons and initial mythic, you know exactly how SW works (which can be far worse than Barrage imo in Mythic+ settings) and how distance to target changes the path that SW takes (it makes a wider arc at farther distance, which is where people tend to mess this up). You should know which angles to pull each trash pack, if not at least a general understanding of how SW can pull. Further, MM actually has lots of ways for you to reduce your big 3 minute cd to make it more quickly available in Mythic+, while BM has no such thing for its big cd (Stampede). MM, you have up to 30s reduction on TS through artifact, and you have the legendary boots. Very soon, MM is going to see their TS reduced into the 1.5 minute range. Add in what we're supposedly going to have on our Nighthold tier sets (
http://www.wowhead.com/spell=211331/...nship-2p-bonus), you're going to start seeing people with TS at less than 1 minute CDs. Sims were showing this at 55s with everything, though trusting the sims about tier bonuses right now is a fool's errand. Even if at just 1.5m or 2m, TS will be up more often in the instance at a 2:1 or 3:2 ratio.
If you want to run BM because you're scared to death of aggroing some birds on Maw, fine. Use that as your rationalization. But don't make it about damage. That is not bearing out and in staggered add sims, it literally never was true. And MM looks like it's going to be scaling upwards thanks to TS reductions. I use TS on CD in Mythic+. It's actually an extremely strong CD if you hold it for the last 20% of boss health because Bullseye amplifies the CD with more crit % (Rapid Killing in your artifact increases the crit damage while in TS). So, using it on add packs and having it come up for Bullseye, is actually very strong. Whereas with Stampede, it's fixed at 3m, and most hunters try to save it for boss with all of their other CDs, so they don't look like they are competing with the healer or tank on single target.
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There are very few people going full BM artifact right now. Most are going for 28 MM and filling up the BM artifact as they go (13-18 range). I guess if you go full BM, you probably would be reasonably competitive in Mythic+, if that's all you're really wanting to do. But the argument I've seen on these forums has been that BM at even 13 traits beats MM in Mythic+, which is not something I've ever seen happen in the game.