It is useful. I literally have to use the global section instead of my home feed to see and follow my friendsâ posts because they get buried in my home feed. I do this by turning off all relays except for the ones my friends are using and switching between various ones of those to see different groups of people.
Topical relays are very useful.
I have no idea what âfirst class relaysâ are maybe you can explainâŚ