For people who trade broken-wing butterflies, what are the general opinions on using EIOIO versus Variable Vol models for the greeks and T+n line P&L profiles? I have been testing some things over the past few weeks, and in the current environment, it appears the EIOIO model is a far better and reliable predictor of P&L changes (both in terms of changes in underlying and passage of time) than Variable Vol. For some of the veteran users, has anyone developed an intuition about which type of volatility environments are conducive for different OV volatility settings? I know John Locke's preferred model is Variable Vol, and he states his belief that this model is the most reliable across ALL market environments. I'm wondering if I can do better, and pick and choose the most predictive model for different environments, and then switch between models as appropriate as vol regimes change.