Sorry chaps, but that just does not hold up. So Tolkien changed his mind about things. Not a surprise when you've had an entire lifetime to think about stuff.

But your basing the Ring being left in Barad-dur on a sentence which does not even say that the ring was left at Barad-dur. All it says is that Sauron began to use it once again when he returned to Barad-dur. Whereas in the letter, written in 1958 (so hardly an early one), it clearly states that Sauron had the One Ring with him on Numenor, and, indeed, needed it with him to corrupt the Numenoreans.

Therefore we are comparing a sentence within the texts of the Akallabeth, a sentence which is ambiguous, at best, as to where the Ring was, to a clear and defined statement by Tolkien himself.

In fact reading the statement itself carefully it is very easy, and in fact certainly more accturate to assume this:

There he took up again his great Ring in Barad-dur, and
  dwelt there, dark and silent, until he wrought himself a new
  guise, an image of malice and hatred made visible....

He 'took up' the Ring. Well, the Ring gave Sauron more power in the material/physical world. He may have required a material body to utilise its power, therefore he may not have been able to 'take up' and 'wield the power of' the One Ring until he had reformed his physical body. I do not believe that the term 'took up' means at that point he was able to move the Ring about and certainly Tolkien's statement in his letter says exactly that.

Also, since we are getting into the business of trying to understand unclear sentences, what about this. Sauron 'took up' his Ring and then 'wrought himself a new guise...made visible'. One could almost be forgiven for thinking that before this 'new guise' (new body) was created Sauron was still capable of 'taking up' his Ring, therefore not needing a physical body to actually carry the Ring, couldn't one.

Anyway, what it boils down to is, although Tolkien did indeed change his mind about many things, there is nothing to substanciate the claim that Sauron left the One Ring, which if destroyed would mean his end, in Barad-dur.

Barad-dur held against the siege of Gil-galad and Elendil because Sauron was there and using the Ring in its defence, not because the tower was strong enough, in itself, to hold back the might of the Eldar and the remaining Numenoreans at the end of the Second Age.

Tolkien clearly states that Sauron had the Ring in Numenor and he clearly is not bothered about the ability of Sauron to carry back the One Ring, even when reduced to the form of a Spirit. Sauron put his very essence into the One, why therefore is it not possible that the remaining essence/spirit was able to carry away the object of part of his essence.

I suppose it may be possible that in The Lost Road there is something about Sauron leaving the Ring in Barad-dur, but I very much doubt it. But since I don't have the book I'll have to rely on you guys to investigate it.

Cheers

Padster