The higer the superfat the softer the soap so if you want to know will it last as long than something with a lower SF when it is being used then I think the answer would be no you do however have a more moisturizing bar of soap....
If you mean being stored lasting longer - that one I don't know but maybe someone else would...
I agree with Lindy .. the harder the bar, the longer it lasts. If you have a softer soap, a soap bag is a great alternative because you can even use the mush/slivers.