Even if you manage to subvert 99% of the mining power to another chain, there is absolutely no way in hell you will be able to keep that a secret. Miners are going to notice.
In the logic of the attack I would not mind when they notice. Since I have 99% percent of mining power I do not care what the remaining 1% of the mining power does.
I suppose we have a misunderstanding with regard to the phrase "subvert 99% of the mining power" as it was used in an earlier posting. I understand it as "I own 99% of the mining power". It looks like you understand it as "99% of the miners are in my pool and they might also leave my pool".
I agree completely: If "my" 99% of mining power just is derived from miners in "my" pool - the miners might notice and might leave my pool. And still, even in this situation: Would they do so if they realize that their payoffs are larger in my version of the algorithm? They are getting 51 BTC (or 500 BTC) in my version. Is it tempting to move from a 500 BTC per block operation to a 50 BTC per block operation? ;-)