From Canon USA's specs on the Rebel T2i, I see that it has +/- 5 exposure compensation where as most others have +/- 2 or 3, yet at the same time, it uses 14-bit RAW format just like many others. I am just having some difficulty to grasp the concept of +/- 5 exposure compensation. Does that mean the sensor in T2i has a much wider dynamic range than the others?
No. It just means that you can shoot from +5 to -5ev with respect to the metered exposure in an autoexposure mode (e.f. Av or TV or P). I suppose this is for HDR addicts. It's not expanded dynamic range unless you combine shots taken at various settings - hence High Dynamic Range (HDR)
If the DxO Mark site is correct about dynamic range then Canon's sensors are actually trailing a little when compared to some current sensors made by Sony. Those are getting used by Nikon and the Pentax KX. RAW DR is a factor of influence in DxO's sensor evaluations. Canon's push to high pixel count hasn't helped and I find it strange Canon has gone that route. Owning a Canon S90 P&S and seeing how well it does in low light makes me think Canon may be rethinking this craziness. That can be seen by their pixel count drop in the G11.