[Raynor]

Originally Posted by Formendacil

I would agree that, in pretty much all respects, he is an Elf's Elf.

Then, if I understand correctly, we are in agreement .

Originally Posted by Legolas

Likewise, Tuor does not 'become an elf.' He is still a Man; he is simply granted the same grace.

I doubt this is a correct interpretation:

Originally Posted by Of Tuor and the fall of Gondolin, Silmarillion

But in after days it was sung that Tuor alone of mortal Men was numbered among the elder race, and was joined with the Noldor, whom he loved; and his fate is sundered from the fate of Men.

Why would he be numbered among the elder race if he wasn't an elf himself? How could he still be a Man if he doesn't share their fate anymore?

The fact that he shares their abilities remains unchanged by his fate.

I am not aware that Elros displayed any ability I mentioned - nor that any Man shared them. This are specific Elvish traits, gifts of their race.

He would share their abilities in any event.

Why? Is there any sign he had them before he made the choice?

Likewise, Gimli "lived the life of one" on Tol Eressëa, but that does not change his fundamental kind. He is a dwarf, and accepted as a dwarf.

I would call this a false comparison. Gimli didn't make any choice (as Elrond did); he was a guest in the elves' home. He would die there, to the manner of his kin; Elrond would live to the end of the world, as elves do.

Which actually brings me to a better description. Elrond's phenotypes are all, or at least more often, Elven where there is a difference between Men and Elves. However, that does not change his genotype. He is still Half-elven.

What sets apart Half-Elven from Elves from Men among them (in genotypes, or by whatever criteria you consider relevant)?