This is what my novice ears got from hearing both.
First, B&W 703's tower speakers. My first impression was how clear they sounded. I guess what Im saying is they sounded realistic. With only 2 bass drivers, I didnt get over powered by it. The soundstage to me seemed very complete as I was listening in a mock living room about 15 x 20. I didnt get a chance to listen to a variety of music or a movie. Initially, though, I liked what I heard. Sorry for the lack of technical info as Im am just learning.
Second, the Paradigm Studio 100 with 3 bass drivers. To me is wasnt a good comparison for the additon of 1 extra driver as opposed to 2 in the B&W's. The salesman kept telling me they sound bigger than they really are. Well, for one, they are a large speaker IMHO. One thing that bugged me about them was the overpowering of the bass. It seems that is the only thing that stuck in my head. I dont recall hearing alot midrange or tweeter clarity( I could be mistaken of course).
In short, Without having spent more time with either speaker, I would have to say I prefer the B&W 703.
Rex