Delegates can easily avoid this by using relays in such a way that the delegate is connected only to relays. Relays will not forward invalid or duplicate transactions.
Valid transactions are OK provided they have sufficient trx fee. It is OK to flood the network with transactions. You'll pay the price.

However your method will reliably filter out unprepared delegates. That is a good exercise I was meaning to do for a long time.

Delegate nodes should not allow incoming connections.   There is a flag set to disable incoming connections just for this purpose.

every TX you send to the network will have to validate .. especially concerning the min. relay fee ..
my guess would be that such an attack is "expensive" .. though probably no too expensive in devshares ..
this would also show an upper limit for TPS that can be handled by that particular delegate .. results would be very interesting

So the newly designed processor which supports distrbited computing will be better? But in what sense? Efficiency, scalability or what?

How does studying dpos, nxt and ethereum help?

Come-from-Beyond, here's a nice honest way to approach this: discuss with the community what kind of attack you plan on doing before executing it, and then proceed with the attack only if the devs/community tell you that your particular attack will not work.

I think the lack of real socio-economic incentives within DevShares will make this data not very useful. The will of shareholders is an essential piece to this puzzle; people just don't care enough about DevShares.

For this attack experiment to be useful, people have to start caring about the security of its network. There will be 'attackers', and 'defenders', each putting value into the shares for different reasons. The upper bound of the token value will then be defined kind of like an auction of the two sides; who is willing to pay more to control the network?

I think this should be a competition, with defined rules, and money put up by both sides. The pot is split up proportionately to the donations of the side that wins. This will double as a prediction market indicator of the success of the attack.

Are you an Attacker or a Defender of DevShares?