I came back to WoW in August 2015, so I missed HM and BRF when they were current content (only done them in LFR). I've cleared heroic HFC in PUGs and I'm thinking I might try for mythic HM/BRF one day to get the achievements, but I'm not sure how feasible it is.
How hard are mythic HM and mythic BRF with current gear? I'm talking about your average PUG raider, maybe around item level 720 or so with a maxed or near-maxed legendary ring and maybe also some set pieces.
Can you just curbstomp them if the entire group is geared enough to do, say, heroic HFC - or can mechanics still wipe you?