Wide angle and Filters

Hello first post and a question.
I am going on a landscape photo tour soon so I am considering a Wide zoom.
I have a T2i (550d) kit lens, 70-200 F4L IS and 50 1.4.

I am not limiting myself to landscapes long term, but I want to learn to shoot them better.

I am wanting the Sigma 8-16 but I don't know if the lack of filters would be a problem. (I have never used a filter other than a UV as a lens protector)

Could there be a time when I would be kicking myself for not getting the 10-20 or the Canon?
Any help/ suggestions would be appreciated.
Knights