I can also confirm that the RetroGamingCables.co.uk Sega Mega Drive 1 cable works fine with my Japanese MegaDrive. It’s the standard version, which has a 470ohm resistor and 220uF capacitor on the Csync line. It’s also got 75ohm resistors and caps on the RGB lines too. No sync LPF is needed to get a good image. Although on my TV (Samsung KS7000) I have to set “Allow TVP HPLL2x” to OFF, and “H-PLL Pre-Coast” AND “H-PLL Post-Coast” to 3.
On the topic of those “Packapunch” cables, I’m thinking of getting a few….do you guys think there’d be much of a difference in image/sound quality? I believe the only difference is he uses individually shielded conductors, rather than just one overall shield.