The carbon thread inner shaft reinforcement is working fantastic on mine, I recommend it. Today it fell off a table, hit a wall about 6 feet up and fell to the ground, and blade struck my hand. I had to straighten out the flybar a couple times but the inner shaft didn't break.

I took about a 6 inch length of about 5 carbon strands, kevlar would work too. Wrap it around the top of the shaft down to the upper blade drive pins. A few drops of thin CA lock it in place. Don't glue the square flybar drive peg into the shaft, leave it press on so it can pop out in a crash. When putting the flybar back on the weights need to be in front of the upper blade leading edges, not behind.

With that problem fixed the little bird is holding up great, knock on wood.