They consider the possibility of using a shared private key to minimize extra space and suggest using MuSig on the two participants to reduce OP_CHECKMULTISIG/OP_CHECKSIGADD. Furthermore, they propose removing the need for an explicit OP_CHECKSEQUENCEVERIFY or even separate keys for state and update paths. The proposal that does not include OP_CODESEPARATOR is presented, where nSequence is 0 for update transactions and non-0 for state transactions, and both have nLockTime equal to the required index. Participants also discuss the chaperone signature and the use of anyprevoutanyscript/noinput in taproot collaborative spends. Finally, it is noted that the BIP isn't final and they don't know yet if chaperone signatures will eventually be needed, but it's useful to make sure that Eltoo could support it.