I have not tried this, but I would shy away from it. I wouldn't trust the sensor not to overheat, you would need to convert the signal to sdi to get into your switcher etc. Why not just rent a lipstick camera?
The overheating issue is pretty much my only concern. The events last about 1hr. I have broadcast switchers that accept a slew of inputs, so that isn't an issue. These events are all over the country, so instead of hauling around my HPX300's - if I could pack a 7D with a 70-200 - that's less stuff to carry (because I bring the 7D anyway to document the production behind the scenes).
Are you looking to have it record at a remote location, or just go live to the switcher ? If it's in a conference room most of those are cooled and over heating shouldn't be a problem.
Try it out, and give us a good field report of how it went
I would stick with the video cameras for this one. DSLR's are not designed for this use and I would not risk pissing off a client if it proves unreliable.
I'd do this set up with a proven camera first, where you'd have no question about it's ability. During these events you should have a couple hours of down time, if not a day in advance to set it up. Why dont you just leave it on, plugged in before the event during set up/faxing time once you got the switcher fired up and see how it goes ? If it runs for an hour/two, perfect. It's ready for prime time.
Thekeygun: Yes I have smaller cams around that I could use, but always thinking outside the box.
TimKay: I have done these events with my HPX's before no prob, just wanting to travel with less gear. I HATE cramming gear in overhead bins. Will report back after test. If it does work, the next project is rear focus and zoom controls.