I'm in a similar boat. I'm 5'5" and currently have a WSD XS road bike. I'm still not sure that its the right size (looks small, but feels alright), but with my short torso and longer legs the LBS thinks it's the best choice for me. I think it just makes it harder for me to decide on which size TCX W to get.

Good luck with your decision. I'm going to keep an eye on this thread for some tips I can follow.