After giving this much thought, we propose to standardize on payment transactions for block scoring, in particular in combination with merkle-proof of the payment transaction as part of the bid.
- Payment transactions represent the actual block MEV value for the proposer, accurately reflecting the “bid value” a proposer uses to choose between multiple bids.
- Currently 5 of 7 relays already use payment transactions. Their bids would loose out against bids with inflated value by a regular transaction to the proposer feeRecipient, even if the actual additional proposer value is higher.
- mev-boost can easily verify the merkle-proof for inclusion without additional complexity, whereas verifying proof of balance difference would need mev-boost to additionally connect to an EL node.
Lastly it’s worth mentioning that there’s ongoing work to enable profit-switching in the beacon node (see also [RFC] Engine API: Add block value in response to engine_getPayload · Issue #307 · ethereum/execution-apis · GitHub).