What you said is why, in what I wrote, I left it pretty much up to the individual to decide. I admire your fortitude in surviving with an Atomic 4. That engine is an amazing survivor. There are about 20,000 still in service out of the more than 40,000 made around 30 years ago. As you said though, you have to know it's limitations. I have investigated a few fires on boats that had Atomic 4's. It was almost always due to lack of service or substituing auto parts for marine
I replaced the entirety of the fuel, vent and exhaust system in 2005, including going to a Vetus waterlock instead of the stupid and rusty Onan waterlift, and she runs very well. Gas doesn't bother me, because I respect it and I sniff the "carb side" and give the engine a wipe on occasion. I also have a fuel line shutoff I can work with a boat hook if I was ever facing a burning block.
The beauty of the Atomic 4, besides its mechanical simplicity and reliability, is that a low-compression gas engine is by its very nature a better choice for the typical recreational sailor in my view. I have run the engine 18 hours since 2006 (although I ran it about 40 in 2005 when we cruised her after a rebuild). Lawnmowers get more hours. Consequently, if you're going to run a cold engine for 15 minutes until you've got the main up, you want an engine that will run to 165-175F in that quarter-hour, so that oil runs freely, rings seat, and every part gets lubed. Do that with a diesel, and you prematurely age it and foul or wear various components.
With my 52 HP Westerbeke in my bigger boat, I motorsail at 1,500 RPM just to get the engine thoroughly warm, because I like to think I know what diesels prefer (start them, run them to a typical RPM, and let them run for hours until they get hot and happy).
Just to avoid a derail, while I would be interested in some future 45 lbs. 2000 W diesel
genset, which would simplify the fuels carried and the economy of diesel, fire safety, etc., I would face the same problem: even a diesel genset won't like being turned on and off several times a day as one moves around the boat's deck, say. So gas gensets, used carefully, have that attribute that diesel, typically, do not.