I don't think this is really a topic where one answer is 'better' or 'more right' than the other. Personally I don't know a lot about Mussolini, I just know he was smart in legally siezing control and solidifying his power in Italy...as far as a speaker never heard him.
Anyway, I don't think this is something where there is only one 'right answer' to. There are many skilled speakers out there (politicians, leaders, sports broadcasters, and just your everyday civilian). There are tons of people out there where if you listen to them talk you are just like 'wow' simply an amazing voice. I don't know if they would all have the same charm as say Saruman, Mosley, or I'm assuming...Mussolini. But, there are several people somebody can come up with to just come out and say 'This person's voice is simply
magical.'
The state representative in my area (Mr. Carano), former teacher turned politician. I had the pleasure of working a long with him in several programs and events and this guy is another one of those vocal talents. He's got a powerful booming voice (though not to the point of annoyance) that really gets you sparked up. He's one of those men that can 'stir the fire in the soul' so to say, and get people behind a particular issue. Where unlike Mosley, this man's words were true and he truly is a class act, coming from the simple life of an educator and rising up in the world of politics.
Point being, is we can sit here and apply several names from the past and present that remind us of Saruman's voice, and not one I would say is more right than any other (provided that somebody can explain their reasoning/belief). I think it's more like Graham Greene's book
The Power and the Glory, where his main characters (The Whiskey Priest, The Lieutenant...and some others that escape me at the moment) are named exactly that. As it's set in Mexico during the revolution to kick out Spain and get rid of any Spanish influence (the main one being Catholicism). So during this time Priests were hunted down and punished as anything at all that had to do with Spain was trying to be annihilate from society. Anywho, Graham Greene purposefully leaves his characters without a name because any priest, any police lieutenant...etc of that time can go to describe and fit his characters. There wasn't one particular priest or Lieutenant that faced the situation the characters in Greene's book were in. But the readers can place all the priests and lieutenants of this particular time period and fit them in with Graham Greene's characters.
I think the same situation is done here with Saruman. Although Saruman is given a name, we can connect any corrupted leader/politician that enchanted people with the power of their voices to Saruman...and each one would be just as 'correct' as the next one.