While I've never made a pumpkin porter, your recipe looks good. I was going to use Roasted Barley in a recipe I recently put together, and I was warned to not overdo it. Maybe a 1/2 lb. of Roasted Barley would make it a little less astringent. On the other hand, what the hell do I know? Brew that sh!t up and try not to drink all the wart!