Hi @Bastien_Siebman,
Thank you for creating this good reference task!
I’m happy now that there’s Messages instead of Conversation. Messages is less confusing with Comments than Conversation was.
It’s great to have two channels for two types of communication, and everything can beautifully fits in Asana 
- Task comments for communication related to tasks
- Messages for communication not related to tasks, or communication related to project(s), team(s), or any combination of members