BUSA usually does a good job of producing plans that you could scratch build from. That said, it would not be the first time that there were differences between the plans and the kit parts. According to the usual theory of such things you would lose aileron effectiveness while the top wing is still flying but in actual practice it might not make that much difference. I've also known people who swore that the lower wing needed more incidence and should stall first. It sounds like your buddie's plane was flying with the greater incidence on the lower wing before the crash. The bottom line would be how did it/does it fly? Was the damage due to a loss of aileron authority?