I am quite sure this has been discussed already, but I was not able to find it...
Variable Print Settings are great, but limited to layers in z. The text "vary the slicing settings for different regions of your print" is misleading because restricted to layers only and not a free part.
Often it could help much if a specific region like the right half of a part could be modified with other settings. Take a look to Slic3r Prusa edition where it is integrated: http://slic3r.org/blog/modifier-meshes
thanks in advance