I have a Trophy with a 220 HP 4.3 Vortec I/O. I do fish the interior lakes as well as a few trips to the saltchuck every year.I have a heater, which is sure nice on the cold mornings. We do fish the lakes during the winter, which requires a heater. I looked at both options when I bought my boat, and have spent a lot of time over the years fishing at Barkely Sound, Cambell River, Victoria, and clearly most of the guide boats have outboards. A guide boat owner once told me one of the reasons he prefer outboards is the ability to quick change or trade in. He said usually cannot finance a repair/overhaul to an I/O but the dealers will sell you a new outboat on time. and, every day the boat is down during the season is costly. I notice many of the bigger guide outfits have a spare outboard at their dock, just in case.
The new I/O have come a long way - they are powerful, economical to run, and fuel efficent. The fuel injection types are very trouble free, start well, and the hazards from carb. backfire are gone.
However my next boat will be 24 - 26 foot, and many of the good fishing rigs are set up for one or 2 big outboards.
Not sure what I will buy, but both engine/drive types are way better than in years past.
I think tradition may have a lot to do with the choice.