in a nut shell lowering the front roll center gives you more on throttle steering, car is less responsive, bewtter on smooth high grip tracks with long fast corners.
Raising the front roll center gives you less on-throttle sterring, car is more responsive ,use on high grip conditions to avoid traction rolling, use on tracks with quick direction changes.
lowering the reqar center gives you more on-throttle grip, less grip under braking,use to avoid traction rilling at corner entry, use under low traction conditions , increases traction and reduces rear tire wear.
raising the rear roll center , use to avoid traction rolling mid-corner and corner exit, reduces rear traction.
(from 710 set-up book)