We made the move from a 2008 C-Dory 23 Venture with 2 x 60 hp Yamahas to a, then new, 2017 RT 26 SC with the Volvo 150 diesel. At the time we thought of the move as being from camping to a motor home and we were right. Whether this is the right move for you or whether the outboard version would be better depends on your intended use. You will probably get varying views here but let me make a start from my point of view.
If you're looking to fish, the inboard is usually too fast to troll even at idle.
Are you one who takes time to make the journey and is happy cruising at 15 mph ~ 2.6 mpg (20mph ~ 25 mpg top speed) or do you want to cruise around 25 mph and enjoy the destination sooner? If the latter, advantage outboard. The inboard is semi-displacement and the outboard is a full planing hull. The beam is carried further forward and the bow is fuller. Great for lift and interior volume but less of a sharp entry into serious waves. If conditions don't allow planing (comfortably) you will be possibly be down at hull speed.
Comfort: You mentioned the engine provided heat but there are other thoughts if you intend to anchor rather than marina hop. Do you prefer the head/shower in the bow next to the bed or in the cabin next to the galley? Compare the overall layout with your intensions.
Outboards are a lot easier to access for maintenance
Thinking of maintenance, either RT will have a LOT more systems to learn and maintain. How much time and energy do you want to spend on that?
That's a start and I'm sure others will contribute. For us, at our mid-70's stage, we are happy cruising at that speed and enjoying the ride, even in rough water. The C-D was a cork and the RT just plows on.
