For what you shoot, 5DII would be fine....
Except for the basketball. The 5D2's AF is not up to that, would be frustrating to use. For sports the 50D you already have is a better choice... or 60D or 7D. Used right both 50D and 60D can come close to the sports/action performance of 7D. It's just that the 7D is more customizable. (However, set it up wrong and you'll get worse results than 50D, I can tell you from personal experience.)
The differences from your 50D, the 7D and 60D are good for about one stop higher ISO. IQ isn't all that different. They can shoot video, tho, which your 50D can't. The 60D doesn't have Micro Adjust, that your 50D and the 7D both have. The 7D has a nice viewfinder, but it's different, with the active matrix/transmissive LCD. The 60D's VF is nearly identical to your 50D's.
I use 7D and 5DII, and have 50D as backup/loaner cameras. I shoot a lot of sports/action, so use the 7Ds about 10X as much as 5DII.
The 5D3 is more verstatile, with much improved AF compared to 5DC and 5D2. I think the folks suggesting you wait for Photokina (in a week or two) are thinking there might be a new FF model coming from Canon... There are rumors of a lower priced, smaller FF model with 7Dish AF. Who knows what Canon might do... it's just a rumor. But there are also 70D rumors... And a 39MP to 46MP model. No one really knows, who's talking about it.
