Mike,
Excellent progress on the arrows, and a beautiful bow to go with it! I wish I could build flight arrows as quick as you have. I am lucky to finish a dozen per year. Hahaha!
Yes, I have used this same technique with hardwoods. One of the first arrow shafts I ever made was an arrow shaft made of alternating strips of hickory and purple heart. During the glue-up, I put a deliberate twist into the shaft to give it a crazy candy-cane look. Billet wood or Massaranduba is a good candidate because it is very shock resistant. The arrow will need to be a little larger in diameter with a dense hardwood in order to make up for the lower material stiffness compared to Tonkin or Japanese Arrow bamboo.
600 yards is an excellent goal for a hand shot all-natural materials bow. Not many have achieved this, but it is certainly achievable given Some determination and your skill. The Turks had a special level of achievement for their flight archers when they reached somewhere near 600 yards. I have to look up what the title is called, but I would like to create a special recognition under World Archery/USA Archery for this level of achievement as well as maintain a list of archers who have accomplished such a feat using all-natural materials equipment. I hope to see you on this list someday!
Alan