I made the switch from iOS to Graphene 4 years ago. I ran both devices in parallel until I was using Graphene for 80% of the stuff.
I've never used primal with this npub because it doesn't support Amber.
I'm a die hard unapologetic Amethyst supporter.
I've experienced the double image post when I've accidentally double tapped the upload button. It inserts the URL twice, which is easy enough to remove.
I have no issues tagging people by putting the @ symbol & then typing some of their handle. It will actually search their bio as well & display people you're following first.
Make sure you've updated to the latest version. Definitely worth installing zapstore & using it rather than FDroid. It's also great for discovering apps.