The carbon spar Q200 was introduced by QAC and not Bert Rutan. Scott Swing load tested the spars to failure using a simple method of putting the spar in an elevated aluminum device with loading at the tip until failure. If the spar didn't sag to a defined height after a certain load and time, it passed and was shipped. Several didn't meet spec and I believe Scott even used one in his Q after repair.
I know a little bit about this as my right spar failed at 200 hours under where passenger legs go, due to a stress riser from the aluminum fixture. I repaired mine back then and the plane now has hundreds of hours on it after failure. People should be very careful at gross weights over 1,300 lbs. Just my opinion.