If INSMED is hiring their own in-house sales force, then VA is a much better headquarters. The availability of sales staff knowledgeable in pediatric endocrinology will be much higher near Richmond than out in CO. There is a huge pool of sales people living in Northern Virginia. Plus you can tap into all of the scientists from NIH, Walter Reed, Research Triangle, Hopkins, Childrens Hospital, etc.
I live in DC and work just across the Potomac in Northern Virgina. The sheer number of sales and marketing professionals in this town is ridiculous. High tech, beef, oil, medical equipment, you name it. There is a large pool of highly qualified sales people concentrated here in the mid-Atlantic seaboard. Add the medical research and easy proximity to regulatory agencies and Virginia is a big X on the spot.