Hmmm.....If I was buying a boat now I think I would still go diesel. I do like the grunt it has and, since I like mechanical things, the diesel installation gives me a pleasure that the outboard did not give. I guess that's just a personal thing. I do miss the ability to accelerate like a bat out of hell and the ability to cruise at about 40 because the hull works so much better at that speed than the 30 I currently cruise at. However, sea conditions sometimes prevent the higher speed anyway so it's not at the top of my list. Also, I've been trying hard to slow down and loose that frantic way life currently seems to be so having an imposed limit is no bad thing.
The perceived lack of space because of the engine compartment is not an issue if it is designed with thought and, in some ways, it is better than the conglomeration of the fuel lines, control cables, fuel filters etc. which make up that generally gruby or greasy area at the stern of an outboard powered boat. The nicer outboard installations have the engines mounted in their own area to overcome the problems of the clutter but then that area of the boat is removed from general use too. Also, you still have to house the battery, have access to fuel tanking and fuel filling and that can all be under cover in the engine compartment.
The boat also handles better because of the lower CG that a diesel installation gives.
On the down side, the diesel installation is vulnerable. The engine is not watertight as an outboard is and it is also below water level so all possibilities need to be considered and precautions taken.
The boat is also much heavier and driving, especially at close quarters, needs to be done with more care.
As for access to fuel, on the west coast there is no way at present you could cruise extensively without fueling hassle with petrol engines. On the plus side, carrying jerry cans does give you some exercise.

None of us know what the diesel situation will settle to in the more remote parts but I'd be surprised if boat owners will be forced to fuel at a petrol station. There are a good number of larger private vessels on the west coast which carry fuel in quantities of thousands of litres and I don't see them being expected to carry it 20lts at a time in jerry cans.
That'll do for now....