This patch adds an option to solidify complex which will make faces which have thickness controlled by vertex weights flat/even. For each face it uses the minimal vertex weight assigned to it to control the thickness (as stated in the tooltip).
This will help users for example in architecture or basic CAD design by finally making solidify work there at all if altering thickness is needed.
Here is an image to show the basic result:

This patch is currently based on D7334, but I think it should without changes apply just fine on master as well as the touched code is in different places than the other two pending solidify patches.