Lack of integration between structure and behavior (e.g., flows, triggers, input to do/behavior)
Limitations of executing behavior that is integrated with structure/ports
Lack of integration between different kinds of behavior (seq, act, stm, uc, timing)
Lack of integration with analysis expressions so that it is simple to create an expression anywhere in the model
Unification of expressions and constraints
Inability to represent structure of I/O and how they are input to different functions
Lack of representation of timelines
Inability to easily create and destroy relationships such as connectors
More flexible pre/post conditions using bdd/instance diagrams (refer to Keith Butler presentation)
Support for software architecture concepts as identified by Ron Townsend
Support for variant behavior modeling concepts