My boat has been marina kept for 29 years and I don't think I will ever go back to towing...its just too much of a hassle hooking and un-hooking especially since I am older. Trailerable means under 18 feet in my opinion...anything longer and you are talking WEIGHT. The best systems are the ones where the boat is lifted out on a cradle (no bottom paint), and not subject to floods and high wind bashing.
This is the most common mooring method in Florida canals. In spite of anti-fouling paint, sacrificial zincs, outdrive still dis-integrated and had to be replaced.
For new owners, my advice is to keep your boat in the marina only if you know you are going to be using it every day...otherwise trailer it and check the outdrive each time it is hauled out. If you are not going to use it for awhile, keep it on the trailer...not in the water.
Boating is still enjoyable to me in spite of the costs.
Cheers, DocWet [Everything has limitations...and I hate limitations.]