I would think this would be a personal preference, however, keep in mind that if you move this information to an alternate name fact the only reports it will show up on is those reports where all facts are listed out (at least to the best of my knowledge). The "Descendant List" would not print Alt Name fact.
I know this isn't exactly the same issue you are having, but I came across an issue with how to record a person's name, and personally, I struggled with how to handle it for a couple weeks. Throughout the years my grandmother flipped her first and middle name, then added a second middle name. I chose to enter it the way she had entered it in the Family Bible, be it mixed up and added to. Even though her birth certificate says one thing, she put it in the Bible this way and this is how (I believe) she wanted to be remembered by future generations. I would think your ancestor would also want to be remembered that way, especially when dealing with nobility titles.