I tired these cookies yesterday. Only change I made was about a tsp of molassas since my brown sugar was light brown. They came out delicious, taste and texture were great. I didn't have the problem with crumbling- I left them on the pan until almost cool before moving. I cheated and used store bought chocolate ice-cream - great flavor combination :)
I bake cookies all the time and these were just too crumbly. I followed all of the instructions and most of the cookies broke or crumbled as I was putting them onto the cooling rack. If you have a peanut butter cookie recipe that you like and know works well, use that and make this ice cream to go with.