RE: When to do the blades modification...
At 18 I was flying a Concept 30 and 1 of the rotor blades came off. I had no idea I should glue to the grips on. As a result I was hit in the thigh with a blade. I had about a 2.5" deep gash from where it impailed me. I had to jump up to keep it from hitting me in the gut. Actually I jumped out of instinct, there wasn't reaslly time to think. The suggestion of suicide is not far fetched at all. I was about 10' from the heli in a hover when it ocurred. Of the course was nearly a total loss as well. Glue the grips on. Save your self money and pain.
Fly safe, have fun.