Dusks' clothing does follow his scaling. The body suit follows it, as does the speedo. So far I only have the clothes that come with him. He is a bit taller than M4 but proportionally he's the same build. Scaling him to 96% makes him the same height is M4.

M4 is the same height as G2 Simon/P6 James, he's just built a bit thicker/more muscular.  Most men that I encounter average a height of 5'10 to 6'2, which is about the same as Dusk and M4, Dusk being on the taller end of that, maybe closer to 6'4, which also is not uncommon in the US, especially not in the midwest or south-east. Without pulling out a measuring device it's just a guestimate. But since Poser doesn't come with a built-in measuring device that I'm aware of, it's a matter of using a 3rd party device, and they all seem to use their own methods. Regardless, all 3 figures here follow the standard 7.5 heads rule of realistic proportions. Everyone is not built exactly the same of course.