Check how much more xp you do with your imbued itens compared to your better permanent equips.
More than 20% increase? Worth it.
Worth notice that damage imbuements makes so you deal more damage/hour, making so your leech imbuements (mana and life) are more effective
Gold efficient (life leech/mana leech):
715.000 gold in 20 hours = 35.750 gold an hour = 239 GMP/h
Check how many monsters you kill in one hour with the imbuements.
Check how many more GMPs you needed to use to kill that number of monsters with your better permanent equips.
More than 239 extra GMPs? worth.
So in conclusion you will have to see it by your own doing the experiment, making a few hunts on the same respwn using imbuements and doing it without imbuements so you will see the difference and you will determinate if it is worth it for you.
Since every person has a hunt style , different levels , different skills so I think thats the better way to find out.