I will agree the I/O has more more maintenance, but when I needed a new coil, it was down to the NAPA store and $35 bucks with a 5 minute install...good luck finding a fuel filter for a Yamaha for $35 bucks. The last bellows and u-joints lasted 16 years before I replaced them.
The 1993 engine block cracked after the previous owner ran it overheated (supposedly sucked up a plastic bag). I replaced the engine with a NEW factory Volvo 5.0 and had the outdrive rebuilt for...$6000 most of which was labor. I got a quote for a replacement 200 Verado powerhead was $14K plus install.
My I/O is buried under the rear deck, I doubt it is louder than a four-stroke outboard. I leave the engine hatch open when I start it so I can hear it.
Did I waste two weeks getting the carb rebuilt? Yup, only because I thought it was too complicated for me. Now I know the job was a LOT simpler than I thought. I like simple stuff, like me!
Winterizing IS a pain - seems like every time the boat is winterized (had the shop do it to preserve my warranty
) it had issues for a while. This year, warranty expires
and I will store my toon the way my slip neighbors store their I/O cruisers - in the slip using an engine space heater. No more missing great fishing because the barge is high and dry!
The new fuel-injected outboards are really good. Hard to accept hanging $20-28K on the transom, though.
To each his own!