I've had Yamaha, Honda, Etec. I've never liked the idea of an i/o.
Then I bought a 40 year old boat with a Volvo Penta i/o because it was that boat or nothing. I'd read about the cost of parts and was terrified at first but came to find out the motor is actually a small block Chevy and even though the outdrive is ancient and no longer supported by VP, my worries were totally eliminated when I bought a complete working spare on eBay for $80.
The drive is so old it doesn't even have trim...just a mechanical tilt to get the outdrive up while on the trailer...but it hasn't been a problem for me especially using two depth sounders -- one well forward in the hull and one at the transom. The transom sounder alarms at about 15' telling me to slow down and the forward one alarms at about 3 feet which gives me at least 20' before the outdrive gets into trouble.
So, today, I'd give the i/o a slight edge over an outboard, but we don't fish.