its not quite the same. saving a state means suspending it; so if you didn't reach a checkpoint for instance you're okay. You don't need to replay that.
With this method if you are in the middle of a boss fight, you'll need to play it through or start over again if you kill your gaming session.
That means in the middle of Demon's Souls, when you get the 'Call' to Duty warzone with some buddies, they're going to have to wait for you to finish before you can join them.
Not a game breaker, but a definite nice to have.