Through the use of object-oriented analysis and design combined with variability modeling, a highly flexible software model for the metrics handling functionality of a PDE solver framework was obtained. This new model was validated against usability goals, particularly with respect to efficiency and flexibility. The method of validation together with the results are presented here. The efficiency of a pilot implementation is comparable to, in parts even higher than, that of a pre-existing application-specific reference code. With regards to flexibility it is shown that the new software model performs well for a set of four change scenarios selected by an expert user group.