Changes to BIP-360 - Pay to Quantum Resistant Hash (P2QRH)

The discussion revolves around the technical selection between P2TR and P2QRH for blockchain transactions, particularly in the context of optimizing transaction size and facilitating the composition of smart contracts. The choice of P2TR, despite its resistance against quantum attacks, is questioned due to its inefficiency in certain applications. Specifically, it is highlighted that P2TR unnecessarily increases transaction size by 32 bytes in cases where second-layer protocols utilize covenants without requiring the key-spend option. This inefficiency underscores a preference for P2QRH in scenarios prioritizing compact transaction sizes.

Furthermore, the conversation touches upon the ease of composing primitive CAT-based covenant smart contracts. The use of CAT and SHA is presented as a straightforward method for proving an output is the mast root of two scripts. This contrasts with the complexities introduced by taproot, which necessitates EC tweaking within Script to achieve similar proofs. The necessity for such tweaking, currently unfeasible, positions the simpler CAT+SHA approach as more desirable for certain smart contract compositions. This comparison underlines the technical trade-offs and considerations involved in choosing between P2TR and P2QRH, suggesting that the optimal choice depends on the specific requirements of the blockchain application, including transaction size efficiency and the ease of smart contract composition.