Currently we have "FilterPreviousText", which gives the output of that same filter from when it was last called. Because it is reflexive (looks only at itself), it is impossible to leverage it for any kind of comparative analysis of output, even when a new filter is scripted.
If we could have a new variable that looks at the output of the *previous* filter from when it was last called, then this would open a whole world of comparative analysis possibilities. If no previous filter exists, it could default to the existing behavior of "FilterPreviousText".
What do you think?