I love, and worship!, the T12. A few years ago when I was more able to handle slightly larger boats I built three large tugs with a single T12 and they performed admirably. As Joe says ESC's are a consideration, as too are batteries. I ran mine off of a 12v 7 A/Hr Lead Acid Cell and had no problem in running for an hour or more. Weight distribution with 2 x 12V batteries may be a bit awkward. Can't find any details on 24v Batteries but they will probablybe quite heavy.
John