Hhhmm, I'm going to go have a think about a way to exploit this model. 

Oh the other hand, is note retrieval across relays a problem serious enough to warrant additional automated discovery of relays?  A new user with a fresh client is going to have way more trouble than a long time user with a well curated list of relays. How often does a long time user have problems retrieving notes?

I'm not a fan of relays that bridge nostr to mastodon. I don't ever want mastodon posts filling my feed. What happens when the note that can't be retrieved wasn't actually a nostr note, but a bot created cross post from mastodon that I don't actually want to see, by not including bridge relays in my client?

Will that note be forced upon me?