I think that once you prestige, the bind items level should be removed. I've lost many primal/ promethium items because i was training my dungeoneering again after prestiging and didn't have a high enough level.
I would prestige until you get enough points for Ring of Bosses. It was 5 or 6 depending on your luck. I don't know if that will change with the update, but the ring is way worth the effort of prestiging.
Thank you for this! It is nice to see an actual loot tab of what you can get from these. I also think it would be nice to have a list of all possible drops (not specific amounts of items but just a full list)