I also have multiple vaults. I did the opposite from you and originally started with more vaults and have consolidated several of them. But I still need a separate vault for each book series that I am writing.

Some comments on the "cons" on your list.

- you cannot create [[wikilinks]] between vaults, but you can create markdown links between vaults. Just use the "copy Obsidian link" command and paste the link into your [markdown link](pastehere)

- I only use the daily notes (actually the periodic notes plugin) in my main notes vault. It is easy to have several vaults open at the same time on the Mac, but not on iOS, so you do have the time friction of having to switch between them if you are operating mostly off of a mobile device.

- on Mac, you can just copy the .obsidian folder over to another vault, and it will copy over all plugins, shortcuts, snippets, etc. I use the same settings between each of my series vaults, but a different setup with my main notes vault.