I'm leaning toward a hybrid approach:

1. autopilot for most things for the outbox-model happy paths

2. if note fails to load, lookup the note in mega relay pools, although this approach won't be internet-scale.

3. broadcast things you're replying-to @ mega relays as much as possible to help propagation.

Some people don't like 3 but I think it helps in the 1&2 hybrid approach. I see the damus relay as just a thing to make the experience as reliable as possible for damus users, since I can't guarantee the reliability of other relays.