These would be caching relays, which is a good idea for a speedy and responsive UX. The most boosted, quoted, commented notes would be on the most relays and would increase response times when needed. Sounds like a good idea. 

 Yes! Good point! Boosts, quotes and interactions provide redundancy. An interesting perspective, with a sort of "marketplace" for what's to store & protect :) 

 Yup, for larger media, video and audio, this could be even more signifigant and help with load balancing and bandwidth.