Intel's e-cores are running at higher clock rates than the cores in my NUC box, and likely at much lower power than the zen4 cores. Are they real cores or not?
They are real cores. And they are more power efficient than zen 3 (probably not zen 4) if you are running all of them. They don't scale down well because you can't run just one, you have to power an entire block of 4. Mostly they are area efficient, also read more efficient in compute per die area or dollar.
The problem with them is, we are putting so much compute power in every box that most computer use doesn't need the e-cores unless you're running a ridiculously parallel and long running task. Large compression/encoding/rendering tasks fit the bill but not much else does.
So, as I've heard it put, it's mostly a multi-core-benchmark-asic.
In my general use, I don't use more than ~4 cores, like ever. 6 cores gives me a very comfortable buffer. But I want those cores I do use to be fast. I don't run full out very often so the power at the top end doesn't matter so much. The 12500 or 12600 are the best chips out there for my use cases.
I expect the 7600X and 13500/13600 to fill a similar segment this time around.