[Raynor]

He acted as if he was eaten up with guilt, feelings that Tolkien confirmed in one of his letters.

I don't think that the guilts of which the professor speaks (desire to return as a hero and regret for the ring) are genuine ones - they are called in letter #246 as a flicker of the dark, one blacker than the other. Seeing that Tolkien wanted Frodo to end up "highminded, ennobled and rarefied", coupled with his chosen solitude & dark thoughts, I would say that the hobbits were perceptive and respectful enough to give him the air that he needed, sort of speaking.

With only a few exceptions, Silm recounts story after story of great and powerful Elves and mighty Numenoreans who fell flat on their faces when they tried to combat the power of the Dark Lord.

Well, technically, there weren't any numenoreans before the fall of Melkor.

When the situation is seen in that perspective it's downright amazing that Frodo, with the help of Sam, managed to do as well as he did, despite all his very real personal shortdcomings (and there were many).

Indeed; also, in the letters, Beren is seen as a precursor to the hobbits, sort of speaking:

Originally Posted by Letter #131

The chief of the stories of the Silmarillion, and the one most fully treated is the Story of Beren and Luthien the Elfmaiden. Here we meet, among other things, the first example of the motive (to become dominant in Hobbits) that the great policies of world history, 'the wheels of the world', are often turned not by the Lords and Governors, even gods, but by the seemingly unknown and weak – owing to the secret life in creation, and the pan unknowable to all wisdom but One, that resides in the intrusions of the Children of God into the Drama. It is Beren the outlawed monal who succeeds (with the help of Luthien, a mere maiden even if an elf of royalty) where all the armies and warriors have failed: he penetrates the stronghold of the Enemy and wrests one of the Silmarilli from the Iron Crown. Thus he wins the hand of Luthien and the first marriage of mortal and immortal is achieved.

which puts an interesting, clearer, light on Elrond's words at the council:

But it is a heavy burden. So heavy that none could lay it on another. I do not lay it on you. But if you take it freely, I will say that your choice is right; and though all the mighty elf-friends of old, Hador, and Hurin, and Turin, and Beren himself were assembled together your seat should be among them.