I know few people who are using WP for their news website but they have some issues with performance and too much clutter that is inside wordpress.
What can convince them to move their website to ghost?
And so many more excellent comparisons out there…
https://www.google.com/search?q=ghost+vs+wordpress
To close the deal, you could take them on a tour of the many fabulous Ghost themes made especially for magazines and other complex publications. Ghost can do everything that Wordpress can do, but more simply and efficiently for both development and content management/publication.
And very importantly, Ghost is the future for publishing, Wordpress is the past. Wordpress had its hayday over the last decade and is in decline in numerous ways. Ghost is far more future-proof.
That was pretty convincing.
About themes, I came to conclusion that every wordpress theme can be made into ghost theme. I also did simple page save of 2 themes and did some changes in assets and got it 100% working. But premade clean html templates are better to work with.
Yes it seems you have answered your own question. Let me know if you want more ideas for your sales pitch. What I already posted is just scratching the surface.