Ironic.. I just done putting together my "Kaffe Stout" recipe, and then logged in to see this thread.
I think that boiling the grounds is bad and so is boiling the liquid coffee.
I have nothing to back this theory up other than my 20 years of coffee drinking. Have you ever drank coffee that has been sitting on a hot plate for too long, cooking? It tastes like hell. That's why I wouldn't boil liquid coffee.
Have you ever had cowboy coffee? I've done this a few times when on long backpacking trips. Cowboy coffee is just a pot of water that you throw coffee grounds into and boil it. This, also, tastes like hell.
so, based on these coffee experiences, my plan for the coffe was to brew up about 8 to 10 oz of espresso. Then, when I turn the heat off on the boil, I would dump that in and let it sit for 10 minutes or so before chilling the wort.
Never boiled the grounds... never boiled the liquid... lots of coffee flavor in there.
-walker