There've been a lot of lessons learned flying this machine. My son loves it and I have every confidence that the plane will take care of the troops as long as the pilot takes care to follow his training as is true with any type aircraft.
The last operational loss, I believe, was an Air Force Model that the pilot flew into the ground. Even at that, most of the occupants survived.
As an aircraft engineer I believe most crashes could be considered flying into the ground, LOL!
I personally believe that the V-22 is a horribly foolish design that lifts itself from its extremities in a balance critical fashion when it could do the same job better if the rotor or coaxial rotors pivoted from above the aircraft's center of gravity along the aircraft's center line to in front of the craft. I personally believe the design was drawn up by an artist, and then forced upon the engineers. Unfortunately simple, stable, and effective were abandoned in favor of the "cool looking" Rube Goldberg designed contraption that is the V-22. Best of luck to your son. I hope he stays safe while protecting us.
If I had my way Marine 1 would be an Osprey and Obama, Biden, Reid, and Pelosi would all ride on it together.