Modeling the cost of detector controller support in a multi-instrument observatory

Multi-instrument observatories have followed two different approaches regarding scientific detector controllers: The ESO approach, with standard detector controllers for all instruments and the Gemini approach, with individual controllers for each instrument. Observatories may consider the transition to standard controllers in current and new instruments when pursuing objectives such as reduction in engineering resources and improvement in data quality. Both alternatives have their pros and cons, but it is sometimes difficult to justify the transition. The entrance of open-source projects to the detector controller scene may help changing the paradigm in this area, especially if investment in hardware is reduced. The problematic is discussed here, with emphasis in modeling the real costs of supporting multiple detector controllers in an observatory, in an attempt to justify the use of standard detector controllers.