It's been a while on this thread, but I just found it. A careful reading of Julia Izard Hemenway's book will show you that while she speculated on a connection between the family of Ralph Izard of SC and the Cape May, NJ Izards, she states clearly that she could not establish a connection. There may be one, but it is way back in Europe.
I have a lot of information on the Izard lines from Nicholas Hoffman Izard and Rebecca Whitaker. One of their sons was Mark Whitaker Izard, a territorial governor of NEBRASKA. This has caused a lot of confusion with the territorial governor George Izard of ARKANSAS.
Most of my information is posted on Cyndi's Tree on Ancestry.com. (Cyndi is my daughter.)