Agree with all you said. I do question your source (not you) about the 10%. Based upon my unscientific observation (I was there 65/66) there were nowhere close to enough Guard and Reserve troops over there to achieve that kind of KIA number. But hey, that was just my experience. Can you kindly point me to your source?
National Archives, Statistical Information about Fatal Casualties of the Vietnam War, scroll down to DCAS Vietnam Conflict Extract File record counts by MEMBER COMPONENT CODE ( Service Component) (as of April 29, 2008 )
A point of trivia, you may not know that a National Guard, Airborne Ranger Unit served with distinction in Vietnam.
http://www.archives.gov/research/military/vietnam-war/casualty-statistics.html#branch