Everything i have researched is that a dd hub is pretty much maintenance free versus a mid drive. Having owned 2 dd hubs and 2 geared hubs i have no expeirence with a mid drive so i can only speculate this theory. please feel free to correct me if i am mistaken. I think both have their merits and in the end it is a personal choice to whatever works best for you. Good luck to the op and hope it works for the intended purpose.