I doubt that Saturn emulator will ever run at a decent speed on the Dreamcast. There were very few dev houses that could really get both the Saturn CPUs to sing in harmony (Saturn, Treasure, and Capcom are a few that come to mind) but those are pretty big power-houses. The little guys are kind of left out in the cold, as there's not many good docs out there.
In short, don't hold your breath (for DC or Xbox). Nobody would rather see this than me, but I've given up all hope.