Split the pool in two or more bells is my suggestion.
Do you understand how the attack works?
Further, he has no real control about that. Who does he kick out of one pool? Will they move to the new pool? If they do, so what; he is still the operator. Nothing solved.
What has changed recently, however is that instead of just two dominant pools, there are four major pools [one very new] and further, the attack you are worried about can only be theoretically executed when > than 50% of the hashing power of the network is in the hands of the attacker. In practice, to earn any significant money before discovered, the percentage would have to be a bit greater than 50%, not just barely over 50%. How much more? I cannot say.
What I can say is that the scenario that spike deepbit above 50% when I was worried about it is much more difficult to orchestrate [but not impossible] due to the increased number of pools. Last check shows deepbit at perhaps 35% of the total network hashing power (rough estimate based on the pie chart ... the numbers are there if you want an exact amount).
Now what you should worry about is why does the block/hour count seem to increase dramatically a day or two before the next difficulty increase? Somebody is putting massive hardware online and apparently strategically. Frankly, I don't think that is good for the network as it will normalize with difficulty increases, but drive smaller miners out at some point leaving heavy hitters spending loads of electricity for a low number of bitcoins [so, they only way for these heavy hitters to remain profitable is to drive up the price of the bitcoin through trading ... a potential bubble]. I REALLY would like if somebody was able to do the forensics to discover who these people are. Are they game changers [new custom hardware] or just very large number of GPUs [still not good]. Honest individual doing stupid things with enough money to burn that they don't care, or are they using bitcoin to take what they can and go. I am a cynic and thus expect the latter. Also, it seems that financial institutions have a stake in destroying bitcoin and so does nearly every government on Earth that collects income taxes. China comes to mind as a potential player. Big banks another. Digital mercenaries working in the interest of the federal reserve and IRS of the USA also come to mind (they don't even have to pay, since the large miner(s) could manipulate the market price fairly easily I think). AMD has a big stake as well, since they sell most of the cards used in mining; however they would be under obvious scrutiny for market manipulation. AMD is probably quite innocent in the matter, but enough money drives the sane in .... insane. Market cap of BTC [if all sold at the going rate] is $0.12BILLION ..or if you like $121MILLION better, then use that. Corruption and market manipulation become a much more likely reality as that number grows.
At the moment, I think tearing apart the worth of the bitcoin economy is a bigger threat than the double spending attack [but of course, watch out for all avenues].
For those that dove into bitcoin mining on credit [building several large rigs], you took a huge risk of getting burned (obvious some have already made out like bandits, but most ... I doubt it).
. 0 is completely invalid, because simply put, you are not mining so it doesn't matter what the percentage fee is.