Most consulting organizations have a cookbook approach to due diligence:  data requests, interviews with key technology leaders, and write-up of the findings.  Having had a seat on each side of the table multiple times has given me the understanding and tools to get to the risks beyond these approaches.  Engineering leaders want to hide their technology warts and it is essential to approach the fact-finding process in such a way as to earn the respect and confidence of these leaders to truly uncover the risk factors.  Furthermore, it is equally essential to translate these technical risks into business risks in a way the client can fully comprehend.