The best method of reducing the risk of the functional/technical divide is the Hybrid consultant.
A Hybrid Consultant has experience of both functional and technical roles, and appreciates the different points of view and mindsets associated with each role. Their experience in both role types allows them to streamline the delivery of customizations, foresee problems when they exist.
A Hybrid consultant operating in a functional role can get closely involved in unit testing, ensuring the technical consultant understands the design correctly, and preventing issues occurring during later testing phases.
A Hybrid consultant operating in a technical role acts as a safety net for any design issues the functional consultant may have missed. Their ability to understand the functional aspects of the design results in more accurate unit testing, and greater accuracy in later testing phases