Firstly, J2C is a derp.
Secondly, you have to be very careful as cable companies are trying to cash in on people's confusion to sell them new cables. According to the spec, there are not 2 types of cable. 12v-2x6 changes only affects the ports on the GPU and the PSU. NOT the cable. Cablemod and MODDIY however made some small tweaks to their existing 12VHPWR cable (nothing to do with the spec, their own changes) and then started selling that new one as a '12v-2x6' cable. They also both told people they recommend the '12v-2x6' cable for 50 series cards.
There are however several different pin types from different manufacturers of connectors and if you bought a bunch of these cables you would probably see a random assortment of each. Different people say different ones are better. I am 99% sure though that the specification does NOT recommend one over the other.
Is it worth getting an ATX 3.1 PSU for the new ports? No one can confidently say but it's looking probabl those changes achieved diddly squat in resolving the melting issue. All they do is confirm the cable is seated correctly, not that the pins are making contact. Hilariously though, in that J2C video you can see they don't really even achieve that. To quote Der8auer "The sense pins are only sensing themselves therefore are sensless".
Also, even if we do determine that some cables are better than others, it doesn't really mean much. The lack of safety measures still means a flawed cable fails badly and causes lots of expensive damage/possibly a fire risk.
TLDR; just wait it out and see what happens.