.... I need to be able to stream ALL 4 cameras, all at once,
And... with broadband connections the way they are now... we are so close to being able to do that. Back in the old days (showing my age here) we used to count the KB of data we used to create a Web Page... because it so effected loading time.
But even though the Internet has got much faster than it used to be....
streaming four cameras.... that's a lot to ask. That would mean the transfer of a lot of data. Assuming your going to pay for a commercial (business class) broadband connect at both ends (camera/sending and viewing/receiving) you will still likely get a reduced frame rate.
Live viewing is normally around 30 frames per second. Often even with a great connection... and only one camera it can be reduced to 15 frames per sec. That's why some Web Cam or IP videos look choppy. With four camera views.... you many see reductions around 4 FPS (or less). Once you see that in action.... you will see why X10 designed their system around the camera switching technology.