We illustrate the use of recent, non-trivial proof techniques for weak bisimulation by analysing a generic framework for the definition of distributed abstract machines based on a message-passing implementation. The definition of the framework comes from previous works on a specific abstract machine; however, its new presentation, as a para-metrised process algebra, makes it suitable for a wider range of calculi. A first version of the framework can be analysed using the standard bisimulation up to expansion proof technique. We show that in a second, optimised version, rather complex behaviours appear, for which more sophisticated techniques, relying on termination arguments, are necessary to establish behavioural equivalence.