I would say that weaker Imbues are worth of consideration only at low levels- I would say till level 100. They will help you during the hunt, however, you definitely do not need Powerful Leech or Void at that point. Also, you will be changing your weapon and armour often- which does not correspond to each other with the same levels, therefore, I would suggest that It will be a complete waste of money to place Powerful imbument on one item (which you will change in few levels)- unless it is only one place where you can put it and you are going for VERY intense levelling/ hunting.