We just finished our latest set of tests, and I can now say that the presentation tool is ready for action! We have made a switch and are now using InstantPresenter. I think everyone involved felt pretty good about the quality and performance of the product.
It's easy for everyone attending to connect with InstantPresenter. However, we need to make sure that everyone presenting has a chance to connect ahead of time just to be sure their computer is configured correctly. It doesn't take any special software or hardware (other than the microphone for the presenters), but it's easier to make sure everything is working before the convention.