There's an option when exporting from WED (A7) to MDL7 for "Faces Separation"--if you choose that, then you don't get that broken-up look with different shading for different blocks (with those "seams" you're seeing in that left picture). What you get instead is the consistent shading effect across a number of different blocks like in the right-side picture. So there's something going on there with geometry/shading, but it doesn't necessarily mean the model needs to be built again from scratch. I had this same problem previously with A6, and nobody really had an explanation for it, but now I see the difference in A7 and know that one does not have to rebuild a model to fix this.