Here's pictures of the system with everything built in
S-video from a sega genesis model 1 with a cxa1645 installed:
S-video from a sega nomad:
S-video from a genesis model 3:
I wasn't expecting this but the s-video from the genesis 3 is even better than the nomad. And the audio is just like a model 1 but clearer. The only downside is there's no longer any stereo separation.
Still easily the best model of the genesis is my super modified genesis 2.