Hi there. I am thinking of purchasing a new lens for my Canon EOS Rebel T1i, I have the 18-55mm and the 55-250mm lens, but I saw the Canon EF-S 18-200mm 1:3.5-5.6 IS and that would replace both of my lens so I don't have to switch back and forth. Now I found the that Sigma makes one too, the Sigma 18-200mm f/3.5-6.3 DC OS HSM, now I can't decide which lens to go with, the Canon EF-S 18-200mm 1:3.5-5.6 IS or Sigma 18-200mm f/3.5-6.3 DC OS HSM, the Canon one is $779 where the Sigma is only $579. if anybody has any suggestions please let me know, it will be greatly appreciated. Thank You.

One more thing, would there be any benifit of buying the Canon lens because I am using a Canon Camera, instead of a Sigma on a Canon camera?
and would I have any compatibility isues if I don't use a Canon lens?