Thanks for a great message Dr. Chris. The GI of Watermelon as I've seen around the internet has been rated between 70 and 73, making it a high GI food. I'm not sure if you recall, but further down on this forum I posted the results of ingesting huge amounts of Watermelon post fast, and the tingling I experienced as a result.
I'll investigate the GI ratings of other fruits, rather than making a quick/rash decision to ban fruits altogether.