IO devices

Can some one explain the advantages of using AJA and Blackmagic devices in FCPX.
Capturing uncompressed video isn't something that is much of a concern to me. Monitoring for color correction is important. I was doing that with a matrox unit in FCP.

Do I need such a device? Just really ignorant regarding them and why I may or may not need to add one or the other to my workflow.

And how do thunderbolt connections add to the discussion?

They are input/output devices. The advantage is getting out with HDMI HDTV for TV screen monitoring for fun or for client previews, or getting out with HD-SDI for quality assurance and color grading.

FW is not really enough to transfer raw SDI signals. Devices that do this actually transcode the codec on the fly to make it work, and are not ideal. T'bolt carries plenty of data bandwidth to allow enough raw (uncompressed) image data to flow from the computer to the I/O device out to SDI so no intermediate on the fly transcode has to take place.

What Matrox unit are you using, with what Mac, how is it set up, what monitor?