While I agree that Rand's ability is an evolutionary next step in *human* use of the OP, I don't agree with you on why that is. I think the possibility has been there all along, but it took Rand's journey and enlightenment to discover it. I don't think it's simply because he's now been "knighted" by the Creator for being such a swell guy, or whatever.

There are clear limits defined by the culture of channeling, which every POV character believes are hard limits. This may or may not necessarily mean that these beliefs are true in all situations. Since we don't have an omniscient narrator anywhere in the WoT, we can't say for certain.

I disagree that simple death is equivalent to the death of one's entire world, their potential of reincarnation, and that of all of their neighbors and children. I think it's very feasible that a Light-side channeler at Shayol Gul during the Last Battle could be more stressed than Aginor at the EotW.

The "rules" have only been told to us by the characters, throughout. We don't really know what they are. What Rand did violates all of those rules, and RJ wrote that. There are also other phenomenon in Randland that RJ wrote that don't mesh with the OP, like Elyas. The POV characters write this off as "not being a thing of the OP" because it doesn't mesh, but that doesn't mean they're correct. That's the loophole you end up with when all of your narrative comes from POV characters.