I recently replaced a burnt out QL stern thruster with a new Imtra SE130, 24V Twin 5 blade on my 56 ft motor vessel. I am happy with it. Regarding electric vs hydraulic I think you will find electric to be much cheaper but if cost is not a major concern then I would certainly explore hydraulic. If you go electric I would seriously consider a variable speed unit for the bow thruster. I think single speed is adequate for the stern.