I don't actually use the old circuit as-is, I use 500ohm pots and adjust each circuit manually instead of using the canned 75/33 ohm resistors. Those resistor values shouldn't cause the chroma problems present in those screencaps. I'd scope out the signals and offer some input but I've just never had it happen, through all revisions of Neo board & probably most Gen 1 & Gen 2 (1145 equipped) hardware.

I've seen similar color artifacts with the newer Intellivision video mod & tweaked it out, but that's almost comparing apples and oranges.

The only potential issue I can see with the simple circuit is the introduction of chroma phase shift, but if it looks good on real world equipment then who cares