every since the 99 level increase thf have got screwed by se. Just as a start all daggers level 90+ should get an increase of +10 to base damage to help get the damage level back to level 75 era and thats just for a start.
As for thf6 , 7 or 8 all i know that in dynamis my bst friend with thf3 gets as many drops as i do with thf8 and he kills in a fraction of the time