Ken Powers SV Aquarius
You asked for opinions.....
With new solar, and lithium batteries the future of gensets has almost come to an end. You can put 2KW of solar on deck with 900AH of LiFePO4 batteries (at 24V). This would life better than getting a new GenSet.
Keep the genset though, you might use it about 50 hours per year, max, with the set up above. And you might even get another 10 years of life out of that Onan. Onan's are very good gensets!