Hi -- The short answer is yes: you can make reasonable synths by taking panoramic sets that overlap by at least 50% from photo to photo. But this doesn't make the most of your photography, nor of Photosynth.
What you need is for us to integrate real panorama "bubbles" into Photosynth, so that the viewing experience can be at least as good as the Flash one on your site. Doing this work is on our task backlog, and we have a great stitcher (the Microsoft Research ICE stitcher) that we can integrate, but we are 3+ months away from being able to begin this work.
If you're interested in working with us on this project, drop me an email. (Click on my name to find it.)