Wubsie nailed it with respect to the healing macros.

My personal experience doing M+ stuff (Up to +5 with 4 Blood DKs and a HPal to heal) is that a ranged team would be superior in almost every case compared to melee. With the all-tank setup to simplify healing you lose a lot of DPS, which is going to set an upper bound on what M+ level you'll reach since they're timed events.

If you didn't have to beat the timer to upgrade your keystone, then I'd be doing this a *lot* more. As it stands, running tanks+healer, I can't beat a timer on a difficult-enough dungeon to regularly get upgrades. As with world quests at this point, I'm fishing for titanforge procs, and I'd rather do other content where I can bring all 20 characters to bear.