I'm a TH9 farmer and I see the value in upgrading the heros. I found the king to be mighty useless in farming with at lower levels but now that he is at 9 he can certainly do some damage and win some big resource worthy raids once in awhile. I only use the heros once every 10 raids or so where they will take full damage. Most raids I don't use them at all or may partially use the queen. Don't make it a goal to level them up but do it when a builder frees up and you just happen to have enough DE.

