Dude Drawing a Few strings int going to show a difference u have to test it With a LOT of strings. I tested it in my Base that worked 2 fonts and ID3DXFont was slower and everyframe counts.
The differences are negligible. It's more a matter of personal preference, because in the end, you won't need 2 billion strings all being drawn at once.
Just search threads by me with text txtboxclasss