Good post, and I am literally on the fence right now. As in, I'm at work, and am SO tempted to go to Target and drop $60 on it over my lunch break b/c I wanted a serviceable 360 baseball game so badly. But the vast majority of everything I read tells me that this is not that game.
Playing the demo might not have changed your mind. The frustrating thing is that unlike 2k8, the REAL problems with this game don't necessarily show up in the 2k9 demo. I played several 3 inning games, and didn't come across the 1B tag thing, or the outfielder running through walls thing, but they're obviously there. Also, there's no way to test out the franchise to see how bad those glitches are.
So, I'm stuck with a 2k baseball game that does so many things right (features, better controls, living roster, etc.) but I know that it's basically broken right now. Yet, I had fun with the demo. Ah, what to do, what to do...