I know that feeling. Unless my guild finds 7 non-mouth breathers to suddenly do Mythic HFC, the only reason I am still playing is the obligation I feel to my guildmates. That and that I am paid up until the end of 2016 via the tokens.
Items in Legion seem to start at 700 in your first zone and go up to 800 for level 110 dungeons/crafted (artifact starts at 750). That suggests a progression of 9 ilvl per level post 100. If you're geared in non-warforged/non-improved heroic, you're probably replacing your items at level 102-103... Warforged+improved will probably last 2 levels more, i.e. a couple hours...
We had around 200 attempts (I wish I was kidding) where there was no progress. Literally none - didn't even see Feast phase. When we finally had a stable 20 people, and those 20 people figured out you can't use any AoE abilities whatsoever, we saw Feast consistently and killed him within 15 or so pulls. It seems like the fight requires near perfection and a ton of practice to get a feel for the pacing of all the mechanics.
