If you're working with the first-party folks at a console manufacturer, whether it's Microsoft or Sony, they tend to spend a lot more on marketing. So if you do end up becoming synonymous with that console you may end up selling a lot more than if your games are spread across multiple consoles. On the other hand, some of the third-party publishers have proved that being multi-console is really great. Ubisoft is a fantastic example of that. Their games are out on every single console and they end up selling a buttload when you add them all up.
I wonder just many units constitutes a "buttload"?