Heard about them but it doesn't look like the idea works very well. As black holes the electrons would have to be more than extremely rotating, which -- aside from raising a number of difficult questions -- violates causal rules by introducing closed time-like curves. My philosophical intuitions could be wrong but until we observe evidence of CTCs then any time I encounter them in a model I conclude the model is unphysical.
Even if it does work I don't think it actually adds much in the way of weirdness to how weird electrons already are. I can at least (mostly) mentally grasp the behavior of a black hole.
Anyway freaking electrons moving in large numbers man watch out those things are dangerous.
Something I found really interesting (going back to the cosmic scale) is if we perform some calculations we find that the universe comes really close to actually being inside a black hole (something I feel is true and black hole cosmology can unite relativity and quantum mechanics.)
Did you read the other article in this field I posted which was about a local causality violation that was discovered? It should be somewhere on this page.
I feel that mathematics lies at the root of the universe (for example, the article I posted about the gaps in prime numbers coming close to matching the gaps in energy levels in atoms) consider the universe to be a cosmic quantum computer and a "natural" AI in its own right- and since the quantum scale is the most basic scale we know about, there should be a direct connection right there. Why causality only enters into the picture at a higher level (along with the arrow of time- to which it is closely connected) makes me think that causality/arrow of time is a product of multiple interactions rather than something basic and elementary. The interactions that go against causality/forward arrow of time get canceled out and what remains is what we experience at the classic level (similar to why we can't find antimatter in the universe.)
Also- on an intuitive level, I feel that being a part of what we observe, it couldn't be any other way. There may be other universes with arrows of time going in other directions (some theories mathematically explore this) but for the denizens of those universes their arrow of time would be forward relative to them, just like ours is forward relative to us. However if we could perceive that universe we may see their arrow of time differently (for example, reverse of ours) and vice versa. It's like being on two different conveyor belts going in different directions but not being able to see the other conveyor belt, so although each conveyor belt is going in an opposite direction compared to the other, the denizens of each feel that their conveyor belt is going forward- because they both are, relative to themselves. Time, like space, is relative. Causality may be relative too, but we don't know it since it is the same for all members of a closed system (that is, the universe.) We don't have that other perspective to glean data from.