I think a very usefull condition would be "If form field is changed". That would be great in updating forms that have a value and I need to cinditionally check if the value is changed.
For example, I have a email field in profile form. It has to check if email is allready taken. Right now I can not conditionally check it if the value is changed. Now it checks every time so obviously this is no good as the username is taken of course (by the user itself). The check would need to be run only on condition that the value is changed in the field.
As I see there is no formfield value =! formfield value to do this.