No, I understand that. The problem (as I see it) is the masternode's quorum can be formed, scrapped and then re-formed with a conflicting double spend transaction all before their votes get embedded into the blockchain by the POW miners.
Well I presume Evan's claim is that honest PoW miners will respect the propagated quorum announcements. So unless the attacker has 49+% attack on PoW, then it is assumed the honest PoW miners will follow protocol. So I don't think the weaknesses is there other than the normal weakness of a 49+% attack (not 50% because Bitcoin loses 1% of its hash against an attacker due to lost time mining orphans). Evan even implied that the minority would fork away from the majority PoW if the majority is not respecting the quorum announcements. That is fine as long as there is no ambiguity, but I had already explained to you up thread numerous cases of ambiguity without my innovations.
Yet as I explained, without a majority of resources, one might still be able to DDoS jam all block announcements by spamming the quorums and block chains with double-spends, or surely can commit a Finney attack as I described.
The other flaw is the ambiguity of which quorum is valid when there is an orphan chain right at the edge transition from one set of quorums to the next (realize this change has to occur periodically otherwise transactions stay stuck on masternodes that might no longer exist or which are unresponsive).
Could you unpack that for me? I didn't follow your math thought.
InstantX required the funds to be presigned over to masternode. I believe the idea in Evolution is all UTXO are eligible to spend through quorums without any presigning.
Last I looked, you needed to lock some collateral away to become a masternode, so acquiring N masternodes has a constant cost, as does acquiring a majority of them with which to perform the quorum attack described above. In regular POW chains, an <50% hash power attacker attempting to double spend has a longest chain production cost which is super linear in the number of blocks.
I don't see how having a majority masternodes helps to commit a double-spend? You need either a Finney attack (controlling one block solution), a majority PoW attack, or sending to both of conflicting quorums with an orphan chain right at the edge of the periodic quorum change.
I am very sleepy now, so it is possible I might be making an error.