In actual fact I am finding Hard to be not much of a challenge now. In elven lands, level 20 and I have avoided the money problems I had in my first hard game. I just upgraded my mage's staffs (2 of them) to I think Archmage staff (+5 intellect and 20% better lightning) and now I am cleaning up in Magic Valley. Off to the Land of Death soon.
I am going to have a break from King's Bounty soon. I have got work tomorrow, as well as The Witcher: Enhanced Edition of which I have only played through the prologue. But I will finish my Hard Mage game first. Ultimately, I think only Impossible will provide a suitable challenge.