Haha, I laugh in the face of Theoden!

Heh, while the kings posess many similarities, and it is true that Tolkien was a Beowulf scholar, I think that you'll have to do better. Hrothgar wasn't born of a higher race of men, with certain powers of the mind that lesser men did have. Hrothgar didn't voluntarily abandon Herot; rather, his men fled for fear of Grendel. Theoden willingly left the halls of the Riddermark for a refuge of safe haven, knowing that the halls were soon, not presently, under atack. Hrothgar didn't have to throw off the oppression of an advisor sent from evil.

I do see what you mean though. Like James said, there are glancing references in the LOTR, but no full-blown "I am from Beowulf". Also, you have to keep in mind that Tolkien once said that he hated even the smell of allegory in any of its forms.