The dimension of the front baffle definitely affect the sound of your speakers.
The quick easy answer to your question is that a narrower front baffle will result in speakers that create a more realistic placement of instruments and vocalist. But, as everything in speaker building, it comes with a cost. The narrower the front baffle, the higher the frequency of baffle step loss. This is a loss of bass response as it begins to diffract behind the speaker- which means that some of the bass energy is lost as it goes behind the speaker instead of toward the listener. If the front baffle is very wide (infinitely), then no energy can be lost as it is guided forward. This is somewhat like cupping your hands to you mouth as you shout at someone. But singers don't cup their hands, nor do guitarist or violinist. Therefore a wide baffle creates a somewhat unnatural sound, IMO. A narrow baffle creates a more realistic image, but will result in as much as 6 db loss of bass frequencies (the starting frequency depending on the width of the baffle).
So using a narrow baffle solves on problem and creates another- bass loss. Fortunately, you can compensate for the bass loss by modifying your crossover. When you start studying crossovers, you will want to see the link below.
http://diyaudioprojects.com/Technical/Baffle-Step-Correction-Circuit-Calculator/Others will have a more detailed or better explanation and hopefully will add to this.
Scott
