> Every single "big bang" replacement I've done, while not exactly a total failure, was extremely painful. The bigger question might be how much more painful w

> Every single "big bang" replacement I've done, while not exactly a total failure, was extremely painful. The bigger question might be how much more painful was it than continuing to try to be competitive (react with new functionality, deliver ongoing value, etc) in the previous codebase, and how much more painful over trying to plan out small incremental refactoring changes during the same time? And... after a certain time period of going through that pain, was the end result quantifiably more useful (testable, fewer bugs, faster, easier to grok/extend/etc - choose your metrics) than if that big change wasn't undertaken?