Brülosophy (standard disclaimer: Brülosophy is far from definitive, but it provides a stronger data point than someone else's anecdotal evidence) did an exbeeriment comparing black patent to roasted barley. They didn't achieve statistical significance in the triangle test, and the anecdotal feedback was that there wasn't a big difference in what the two grains contributed to the beer. I always expected 'ashes' and 'charcoal' from black patent, but the writeup they gave makes one think it's not quite so out there as many brewers believe. Carafa III should end up fairly close, particularly if it's the husked variety and not the dehusked Carafa III Special.
