Although the 7D and 60D can control 430's or 580's, the use of a 580 on camera off camera via a cord can afford greater flexibility in placing the slaves as the 7D and 60D have a limited FOV in controlling slave flashes.
... at least, this is what the manual says. In reality, I was completely surprised by the fov the 60d does actually achieve - the only time my 430ex2 does not fire is when I accidentally cover the ir sensor with my thumb or it is completely blocked somehow else. The ir control strength at least of the 60D seems to be so powerful that it reflects from surfaces near it and triggers even the flash behind the camera.
I get great results INSIDE with Canon wireless. Are you shooting inside or out when you get great results?