There's also the DX/FX question. If you think you'll eventually move up to an FX camera, you have to be aware that the 55-300 is a DX lens, and so only designed to cover the smaller DX sensor.
And another thing - there were two 55-200 versions, with the second iteration (with VR) being a massive improvement. The 28-300 won't give much extra in the way of sharpness over the 55-200 VR, though it will give you a shed load of distortion.![Stick out tongue :p :p](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
And another thing - there were two 55-200 versions, with the second iteration (with VR) being a massive improvement. The 28-300 won't give much extra in the way of sharpness over the 55-200 VR, though it will give you a shed load of distortion.