Jens,
Since the Indivision AGA uses an FPGA, is it possible to add somekind of component video/compositie/S-video encoder into the FPGA? 
There are many VGA to component cables out there (check EBAY)  so you could use the existing hardware.
In regards to the Video Toaster, the current  Video Toaster and Tricaster are built using FPGA hardware allowing Component, VGA, and Composite using a VGA db15 header and breakout cable that connects to the VGA connector.
You already have a home run, but adding these features could really hit it way out of the park. Is any of this possible?