The models I picked up are manual, I did not want electric downriggers at this point. I go with the other school of thought... I like to place mine as far forward as possible ( in this case about 2.5' aft of the main cabin bulkhead), this way the wire stays clear of the props as you manuever. I generally do not use a downrigger behind the boat, not to say it does not work, just another school of thought. Often if fishing more poles then downriggers the aft poles will be used running shallower with a diver over the transom.
I agree with this and I like rotating the downriggers aft while underway better than forward. You can put a downrigger weight holder on the inside of the hull too. The only downside that I can think of is that I also like to have a crab/shrimp davit behind the house... but no big deal if it's in an aft corner.