If you really need it, buy now.
If you can wait, then wait.
Simple as that.
An alternative route would be to buy an older unit and sell it when you see the unit you want; If you have the money to spare, buy the unit you want now, when the new one comes out, order it, transfer your files, and resell it. If you have the money, this is the best way, and you're not out more than a few hundred every year to stay on the bleeding edge.
The price will undoubtedly be the same, or likely, higher.
I don't think you can go wrong, honestly.