I would also highly suggest getting fiber installed. Especially where it's an installation and you don't have to worry about the fiber getting broken, etc.

With fiber, you can get whatever transmitters/receivers you want. So, you can go SDI, HD-SDI, DVI, Analogue, etc.

RGBHV is very much NOT the way to go I would say. Hum, more prone to failure on a single connector, etc.

The video over cat 5 boxes have the problem that they are just using cat 5 cable, they are NOT doing this over ethernet, so it will not work with ethernet devices (hubs, switches, repeaters, etc) Though I don't know of the new one Nev mentioned, as of yet I have not seen one capable of using ethernet for transmission. The other caveat with these boxes is that while they say they can do up to 1920x1080 (example) resolution, their distance at that resolution is much shorter than what they say is their max distance. The max distance on the product listed is normally at the lowest res the box can run at.

One of the benefits to SDI/HD-SDI is that since it is a broadcast standard, the equipment is going to be around for a while. Unlike computer technology, which is in a constant state of flux, the broadcast world stays much more stable, as the level of investment, etc is much higher. People don't change out $100,000 switchers every couple of years. Computers on the other hand change very frequently. It was HD-15/RGBHV, then DVI, now we have HDMI as well, and now the new "Display Connector" is starting to appear.

That is why fiber gives you the most flexibility. Its probably cheaper to install than the SDI route would have cost. And since it is just the transmission medium, you can make it send and receive whatever it is that you need. You can even change it based on the needs of the show coming in.