We probably need to try both. There are lots of decisions to make on what your client displays in order to rectify the appearance of shouting into the void whenever someone you are talking to also talks to someone on a relay you aren't polling. Do that third parties previous posts get retro-actively added to your view of the thread messing up your history? Do your friends replies to accounts you don't see get hidden so you don't get confused? How does the client know who they are replying to anyway? AI classifier?

If you have instancing on one relay is there moderation? If not how do you handle spam?

Man I wish I had more time to code.