X3D-UML utilises X3D (eXtensible 3D) to enable standards-based advanced 3D UML visualisations. Using X3D-UML, 3D UML State Machine Diagrams have been evaluated against actual user tasks and data, using the Sequential Evaluation methodology. The results of User Task Analysis, Heuristic Evaluation and Formative Evaluation phases provide clear evidence that the use of UML extended with 3D is a practical solution for visualising complex system behaviour. RoseRT model metrics show between 56%-90% of state machine diagram work would benefit from such 3D UML extensions; hence the 3D improvement can deliver considerable benefit to organisations.