I'm sure there's some tonal differences between the two tone wise and within the sweep. Different circuits. Kevin makes some great wahs! I had a 6 position vintage wah at one time, and I had sold It only later to find out that it had a 200k potentiometer inside. Had I changed that pot back to a 100k it would've had the magic.
Some of the old TDKs get a bad rep is because the drift in the resistors. Old carbon comp resistors drift over time and that drastically affects the tone, responsiveness and it causes tone suck. My brother scored a near mint TDK wah and that thing nails the shaft song. Hell, it goes up against the other modded wahs we have trying to nail that sound.
It's a head scratcher in many ways because here I've modded pedals trying to get it to sound like that, and yet his stock circuit magically has the sound!
Yes, damn you capacitance you're a sob!