The promise of OpenAccess is simple but powerful: standard interoperability and the ability to use best-in-class tools, regardless of supplier. However, users sometimes experience less interoperability than expected, and find that their choices are more limited than they had imagined. Often, this is caused by choices users make as they migrate from proprietary database formats to OpenAccess. This paper will discuss several common migration pitfalls that can cause custom design teams to experience a lower-than-expected level of interoperability. It will also provide tips to help maximize interoperability, and thus tool choice, for their custom designs through their migration to OpenAccess.