Get the 5DIII, if it's within your budget. You'll gain two more stops of usable ISO over the T2i and 7D, better AF than the 7D, and a faster frame rate than your current camera. IMO, the only current camera that would be better for your needs is the 1D X. A 7DII may come out, but barring some sort of electronic miracle, the high ISO performance of a FF sensor is still going to trump APS-C.
I was shooting boxing over the weekend, poor lighting, fast action (the hands, at least). I needed 1/800 s to have a chance of stopping action, shooting the 70-200/2.8L IS II in the f/2.8 to f/4 range (depending on distance and subject placement, f/2.8 can be too thin). My ISO settings ranged from ISO 3200 (not a single shot lower than that) to ISO 12800.