My team adds a comment to cards where we need to mention people using “@”.

Thanks, we do this as well.  I am still hoping for something that is more suited to long-form conversation.  

Comments work for quick communication that is roughly the length of a text thread but are not really suited for long-form communication that requires several paragraphs of text.  

The other problem with comments is that they seem to be designed to be dismissed, and not stay part of the board for the length of its lifespan.

 

Why not the chat feature within a board? You can link to specific items/objects on that (or any) board. I was going to suggest a board's Notes lane, but I just tried to mention someone with '@' and mentions don't appear to work in the Notes pane.

Have you looked into using Visual Notes with your team @TRS?

One of the things that I feel is lacking in Miro is an easy way to have "long-form" discussions. I am coming from Basecamp. A suggested format for team meetings agendas is: New hire announcements, bonuses, promotions, and other celebrations

In a card sorting session, participants organize topics into categories that make sense to them and they may also help you label these groups. Also, the text should not be too long to read closely in the allotted amount.