cubes? how are they for face washing? do the 300 gram bars last a long time? for those that have used them for face washing, how long do they last you? 6 months? is there any big difference between the olive oil cubes and the palm oil cubes? for those that have used both, which one do you prefer for face washing and which cube is more moisturizing you think? would it be stupid to pay more for a savon de marseille cube when you can get a kiss my face 8 0z olive bar for around 3 dollars at whole foods?