The Canon T2i and Sony A55 and A580 should be able to do what you want without a problem. And Canon's 70-300 IS USM and Sony's 70-300 'G' are well suited for the kinds of activities you want to shoot. While the A55 does have a faster continuous shooting speed, it uses an electronic viewfinder and a smaller battery, so if you'll be away from a charger for a while, you may want to think twice about that one.
Can you get to a good camera shop and try them out? If you can't comfortably hold a camera, if you can't find the controls and commands when you need them, you'll miss shots and be dissatisfied with the camera.
- The lens is the thing.
- 'Full Frame' is the new 'Medium Format'.
- "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.