[thaumaturgy]

There is absolutely no way to rewrite a million lines of business logic without ending up with an even bigger mess. See also: http://www.joelonsoftware.com/articles/fog0000000069.html

[jsmartonly]

I read that article before and totally agree with the point.

But that situation is different from the one we discuss here.

I do not know more information about ohmygord's project, but I basically want to point out to consider non-technical side of it. For example, people in the same team may not technical, and/or think maintaining existing solution is simple. I was in similar situation before, I was lucky to happen to select right strategy to deal with the situation.