Is the roboRio compatible with more than 2 cameras at the same time?

[bdaroz]

Yes multi camera works, but you'll need to roll your own solution as the libs won't work with more than one camera as-is.

One other point is to be mindful of how many you stream simultaneously, and the bandwidth required. For demo/testing purposes you'll be fine, but if you hit a competition field, you'll be rate limited to 7Mb/s.