I have heard it said that I/O powered boats have all the worst attributes of the inboard and outboard. The engine is attached like a car engine so taking the engine off at a repair shop and using a loaner or spare is not feasible like it is with an outboard. I/O's that I have operated don't steer well around docks and such at low speeds because there is little or no rudder action and you have to use throttle to get "directed thrust." I have helped rescue a few I/O boats taking on water at the seal around where the outdrive penetrates the hull.
Boats can be GOOD MEDICINE but you need to know what symptoms you are trying to cure before deciding what boat is best. Want to go fast, feel the wind in your face. maybe feel spray in your face, or have a party platform that will not pull a skier?
Pontoon boats give a lot of deck space for their displacement (AKA weight and therefore cost) and are much more stable then just about everything else. Terrific swimming and party platforms and great for slow or medium speed sight seeing cruises. They permit fishing but they aren't for hardcore bass fisherman. With a porta potty, ice chest, and BBQ grill you can sleep out on the water and not set foot on dry land for the weekend. Takes HUGE outboards to pull skiers and boy will they guzzle gas.
Cost to buy, maintain, and operate tend to increase at the square of the length of the boat (within a particular type, not comparing say a pontoon to a bass boat.)
I was in USCG AUX coastal SAR (search and rescue) for 10 years. I also did vessel safety exams, and taught boating classes. We towed nearly 10 I/O boats for every inboard we assisted. Sure there were more I/O than inboard but not 10 to 1. As this was ocean work it isn't fair to comment on the lack of rescue work with pontoon boats as targets as there weren't many out in the ocean to begin with. We also worked cases inside the bays and areas where pontoons were more popular but I never personally heard of or was out on a case involving one.
Did I just miss it or didn't anyone mention the definition of a boat?
"A boat is a fiberglass hole in the water into which you dump large quantities of money." (Can also be a wood lined hole.)
Pat