Peter Todd introduces the concept of Rebroadcastable Batching Fee Replacement (RBFR) as a method to potentially render CPFP carve-outs obsolete by facilitating a cluster mempool environment that does not necessitate upgrades to existing LN nodes. This approach contrasts sharply with Transaction Cut-Through (TRUC)/V3, which imposes significant operational burdens by requiring all L2 protocols relying on CPFP carve-outs to undergo upgrades, including channel closures and reopenings.

Todd highlights the drawbacks associated with TRUC, notably its vulnerability to pinning attacks due to an arbitrarily high 1000vB limit, which could compel TRUC users to incur substantially higher fee rates under certain mempool conditions. This situation is exacerbated for keyless ephemeral outputs using TRUC, where attackers could easily intercept and pin transactions. Todd's critique extends to the implementation of pure RBFR, suggesting instead a one-shot RBFR system that is immune to fill-and-dump attacks, thanks to its design that prevents the dumping of transactions at the top of the mempool. He argues this system benefits from larger mempools common among miners and the trivial nature of rebroadcasting, which collectively mitigate the impact of such attacks.

Moreover, Todd addresses the misconceptions surrounding CPFP carve-outs, advocating for RBFR as a viable path towards achieving a cluster mempool without mandating updates to existing applications. Implementing one-shot RBFR, however, presents its own set of challenges, particularly in the absence of a cluster mempool. Yet, he suggests leveraging Bitcoin Core's existing fee estimation tools as a potential solution.

In addition to the technical discussion, Todd refutes claims about the economic inviability of certain attack vectors, illustrating how, with sufficient motivation and resources, attackers could exploit current relay rules to execute double-spend attacks or even launch DoS attacks against Bitcoin nodes. His analysis underscores the inherent risks and technical intricacies involved in evolving the Bitcoin network's transaction handling mechanisms, emphasizing the need for careful consideration and robust testing of any proposed changes. For further details, Todd's writings and analyses can be explored through his website at Peter Todd's Website.