[Kuruharan]

The basis is do you think Sauron's orcs were anything like as strong as the Uruk-hai? The only way Sauron could have been victorious would be through sheer strength in numbers through weak puny orcs. Man-to-man the 10,000 Uruk-hai would probably obliviate even 30,000 Mordor orcs.

Unlikely. The physical differences between them were not that great. Historically speaking, the only way that armies are able to overcome disparities of this nature was by great technical (not physical) superiority or brilliant leadership. Isengard possessed neither of those. An army outnumbered three to one, all other things being relatively equal, would get swamped.

Take out the horses & then what result would you have forcasted?

*cough* I thought it painfully apparent that the example I was citing was the Battle of the Hornburg, where the Rohirrim chopped up the Isengarders largely without their horses.

That's a bold statement to make, Master Dwarf!

Not really. We're operating off of an impossible premise here.

Short of Sauron himself, who would force Saruman to hand over the Ring?

I think you just answered your own question.

And, quite frankly, within the safety of Orthanc, we know (from UT) that he needn't fear from Sauron.

I'm rather under the impression that if Isengard was placed under siege it would ultimately fall. Fortresses under siege do not hold out by themselves. There has to be outside help. Where was this outside help to come from in Saruman's case? If nothing else Saruman's physical body could have been starved to death. However, I suspect that long before that conclusion would have been reached, Sauron would have undermined Orthanc and caused it to collapse.

Did he have the military resources to hold off Mordor (and possibly the remnants of Rohan and Gondor)?

No.

We must, however, acknowledge that he had an army comparable to that of the "good" nations- which fended off Sauron for quite a few years.

Hmmm...comparable to Rohan, maybe. Gondor's actual military strength was greater than we saw at Minas Tirith because the southern fiefs were not exactly totally forthcoming with their men. I believe that Tolkien said that many of them only sent a tithe of their strength.

One also gets the impression that up until that point (at least in recent years) Sauron had not been trying that hard but was instead gathering everything together and conserving it for the final blow.

Furthermore, if Sauron had to fight his way past Gondor and Rohan- that would have bought Saruman more time.

Not necessarily. Isengard is actually rather exposed to attack from Mordor. The river could be crossed, and then it is just a march across the Wold, cross another little river, tramp, tramp, tramp, and there you are. Gondor would probably be out of this equation. The Rohirrim might be able to delay Sauron, but I doubt they could stop him.

I personally don't think it would have been long (in a count of years) before he would have been strong enough to crush Sauron with the Ring. The question is whether he would have had that time.

Is there something about Letter #246 that I've been missing all these years?

Let me try this yet again...

Of 'mortals' no one, not even Aragorn...Of the others only Gandalf might be expected to master him-being an emissary of the Powers and a creature of the same order, an immortal spirit taking a visible physical form.
Letter #246

No amount of study would have helped Saruman gain the strength to master the Ring. He was a lesser being than Sauron. He did not have the power within him to be able to do it.

I fail to see how the phrase "only Gandalf" could possibly be up for any other interpretation than in the sense that "only Gandalf" would have been capable of mastering the Ring and challenging Sauron with any hope of emerging victorious.

EDIT: Cross-posted with Boromir88