That is quite surprising. You use the demon while levelling your construction? Is this because of his delivery time? (7 seconds as opposed to 12 seconds for the normal butler) Or something else :o?
7 seconds and carries a few more items plus with the task reward, i believe, that lowers their fee by so much it makes it more worth using the top one.
After the quest 'Love Story' the price of the demon butler is lowered to 7500gp per 8 actions. The human butler after the quest costs 3750gp. (continued)
So you are paying 3750gp extra to save 5 seconds and to gain 6 more items. However if making oak doors the demon butler arrives back too early to make a 2nd oak door, interrupting you. Human>Demon atm
