[Sarumian]

Well, a great thread indeed and I just would like to stress that all Istari who lived in the West contributed to the victory, even Saruman did. Partly his contribution came in a negative way, as his urge for the ring made a tremendous mess and confused Sauron badly enough. As a result of capturing Pippin and Merry by Saruman's uruk-hai, Sauron decided that the ring passed to Isengard and then, after Saruman's defeat, was in the hands of Aragorn - so Sauron sent insufficient forces to conquer Minas Tirith and lost it. And since then The Eye's primary attention was dedicated to the Captains of the West, not to two hobbits in his own domain.

Moreover, before succumbing to evil Saruman was a useful aid to Gondor and Rohan for ages; his role in the White Council was also positive in the beginning.

As for Radagast, he achieved some goals, such as establishing relations with Beorn (which proved to be of critical importance for the entire struggle), watching Dol Gudur and sending Eagles. It's highly likely, he prevented a conscription of any significant number of beasts and birds to Sauron's service.

While the general feel is that he stayed in ME after the War (if he survived it at all), can we suppose that he might have taken a ship to the West before the struggle was over? Can Vallar really blame him that he did not feel he was created for the fight? He went almost against his wish, so why not to go back if he thought, he was of no use any more? Not just elves, but even a maia did once in the past.