My understanding is that homemade bars last up to a week in the frig.
My peanut butter balls, (I was tired of the bars crumbling) usually don't last more than a day at my house.

The protein does not degrade and there is no melting and crumbling and they can be rolled in a layer of melted semi sweet chocolate morsels or chocolate flavored whey or crushed nuts...
I mix vanilla whey in with powdered dry milk for more protein punch.
I'll look into it some more for you.
Hope this helps a bit.