There is significant overlap between posts and feeds. Looking at implementation details (they’re in the same folder, similar code), and documentation (post is mentioned prominently but feed is not) it seems like one was an afterthought of the other.

The only practical difference is that a post can be read on-chain and it is more expensive to make and it can only be done once.

There is no use case presented in documentation where current on-chain (SSTORE) data is useful. I cannot think of any on-chain contract that would want to purchase data using Erasure.

Recommendation: remove Post and ProofHash contracts. In the documentation continue to talk about feeds and posts. But actually a post will be implemented just as a feed with only one entry.

References:

• Post implementation: https://github.com/erasureprotocol/erasure-protocol/blob/4a3d98ce023a264a9f3c7ba62ef77a9207bba5fe/contracts/posts/Post.sol
• Feed implementation: https://github.com/erasureprotocol/erasure-protocol/blob/4a3d98ce023a264a9f3c7ba62ef77a9207bba5fe/contracts/posts/Feed.sol