Jose, many forum members mount their router in a saw table extension. I feel this hinders more than it helps. As sure as you have one set up done you have to take it down to use the other option. Table saw height is another issue; while it is the right height for sawing wood, router tables almost always need to be higher for control and comfort. I understand that this is a good compromise when space is limited or for small portable saws used on job sites. It is my belief that these items work better when separate.
In answer to your question the saw fence is a very poor fence for a router table by itself. You need the ability to expose only part of the bit for many jobs so at the very least you need an auxilary fence to attach to the saw fence. You will also want the ability to make a chip break to help avoid tear out and this will require additional fence pieces.
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"