Holy crap that was a tasty sandwich. I made it yesterday, as well as brewing an ESB, and the end product is awesome! Unfortunately I didn't have the utensils or deli slicer to get the meat as thin as I would have liked, the end product is awesome, and the extra SN Tumbler's I had paired perfect with it.
Mine turned out pretty good but a little dry. Well some parts of the roast were dry, the parts that were really fatty were awesome. Just make sure you get a fatty cut of meat for this and not what is cheapest at the grocery store, like I did.