With the exception of being able to duo the early part, everyone would just zerg past everything in this dungeon as they would in all other dungeons. The main thing that you're failing to realize; if your dungeon isn't the absolute fastest way to get myth/soldiery or get high ilvl items, people are going to do this dungeon once and go right back to Bray HM runs. Even with the small chance of an atma drop, people rather just spam fates since it's a higher chance to get one (in the one hour you claim it would take, you could finish more than 30 fates).