"NTSC and PAL DCTV is probably on the Digitizing end, as timing is important."
That would make sense.
I have the NTSC DCTV, it was the most fun for me back in the nineties. Wonderful paint program, I did my first digital painting on DCTV. I'll post it soon as I can get it off my A2000. I was able to get away with 1 mb chip ram with an 030 at 50 mHz and still play my 3D animations. However it was a big step up using the DCTV with my A1200 060. I rendered them in Caligari 24 and later LightRave followed by Lightwave after Newtek unbundled it from the Toaster. Off course they were only a few seconds long though.