Hi Partzman,
If we stick to classical electromagnetism, Naudin's 2SGen is a simple transformer, of very bad design. Indeed the primary is a toroidal coil, while the secondary is a cylindrical coil, so the coupling is very bad.
How is it improved ? By saturating more or less the toroidal core with magnets, reducing the permeability in some places, the flux leakage is favored, the flux that should have remained confined in the toroid escapes and the cylindrical coil captures it better.
So improving the 2SGen is easy, just take a real transformer instead: we have the same function with an efficiency > 90%.
Now we can assume that there is something beyond appearances, for example that if the permeability of the toroid remains high enough, then even if it varies along the torus, we should not have significant flux leakage. This is the assumption I made, but I have a hard time verifying it, because most probably, this assumption is wrong and the 2SGen is indeed just a bad transformer.
To remotely detect the existence of a flux confined in a toroid is theoretically impossible without using a circuit surrounding this flux (thus whose surface cuts the flux, e.g. thanks to a conductor passing through the hole of the toroid), unless there are experimental biases such as flux leaks. Experimentally, there will always be leaks. What is important to know is their level. With magnets completely saturating the core on one part, it is as if we had an open toroid, or a half-toroid, so obviously we will be able to couple it easily and efficiently to any coil. But we will not have invented anything new. There's no OU in it.
With Smudge we have already discussed a lot of ideas with the potential vector. It is not zero in the space outside the toroid. Can we recover energy from it by the virtue that E=-δA/δt, or more daringly that E=-δA/δx * δdx/δt = -v*δA/δx, maybe this setup would allow it, that's what I was trying to check, taking advantage of this 2SGen topic that Itsu has revived.
When you ask about OU potentiality, it is impossible to say, whatever the setup. Since a science consists in explaining and modeling what we observe, and since we have not yet observed any OU, or in any case there is no consensus on the fact that we have observed any, we have no science of OU, we cannot predict anything.
My point of view is that the potentiality of OU is in anything, with more probability in what has not already been studied than in what is commonplace, but it is a bet, an a priori that we take, to test and keep or reject according to the results. Our initial approach is therefore not scientific. But at least our method must be scientific and technical to obtain the concrete products we need, and that consists in experimentally verifying our daring hypothesis and distinguishing what is conventional from what would be a sign of anomaly. It's hard to say for sure about 2SGen at the moment, although there are many signs that it is not a pathway for OU.