Ambisonic decoders for irregular layouts can be designed using heuristic search algorithms. These methods provide an alternative to solving complex mathematical equations. New fitness function objectives for search algorithms are presented which ensure derived decoders meet the requirements of the Ambisonic system more closely than previous work. The resulting new decoder coefficients are compared to other published coefficients and a detailed performance analysis of first order decoders for the ITU layout is given. This analysis highlights common poor performance characteristics that these decoders hold. Proposed future work will attempt to address these issues by looking at techniques for producing decoders with a more even error distribution around the listener and investigating methods for removing the bias towards meeting certain objectives.