Let me state up front that a lot of this may not work. Having said that...
What would the communities interest be in a video switching application a wee more powerful than On-Air be?
I'm working with the author of CamTwist to turn CT in to a more pro level video switcher. We already have multiple M/Es (although a bit different than a traditional switcher), we have CG, DDR, StillStore and can accept input from any QuickTime capable device, including the Intensity.
I just popped three Intensity Pro cards in to my MacPro in hopes that it would magically work, and of course it does not. So now the question is how much time do we invest in trying to make this work? If I'm the only one then I would probably return the cards and get something else. If not, then I would love to hear what you would use the app for and what features you would like to see.
Today I use the app for streaming a live produced space show to Ustream.tv. The latest betas of the software are resolution independent and even support HD. Trying to find low cost cards that would allow us to stream three or more cameras easily to the web with a HQ archive and I think Intensity is it, but I'm not sure. The drivers and multi-card support sure seems to be lacking.