In my experience, A6 is plenty fast enough on a single core, even for intense or expansive games. I'm fairly certain that the game I'm doing will run fine on a single 360 core, assuming I can build (or discover) the bridge between the A6 DLL and the XNA Build tools. I'm doing an RPG, so the most intense thing for me will probably be the graphics, which should be more than capably handled.

Later today, I'll do some testing with the tools and report back.