A model of how a product should function to satisfy customers is an essential element in clarifying, identifying, and establishing product architectures. Such functional models greatly enhance the generation of creative form solutions to a chosen architecture. A wider breadth of solutions is generally possible, implementing new and stable technologies. In turn, using the recent concepts of design repositories, the possibilities exist to archive, retrieve, compute, reconfigure, and reason with the product forms. To realize these benefits to the fullest extent possible, functional modeling needs further theoretical development. A formalism of function classes, vocabulary, topologies, and methodology is a first step towards this goal. Recent research efforts have focused on each of these elements, where great strides toward repeatable formalisms have been made. Yet, across the engineering design field, very little active experimentation has been pursued to test the veracity of these elements, individually and as a whole. We address this issue here through a preliminary set of experiments conducted at three separate universities. Design teams and individuals are asked to create functional models, in the context of product development, with and without the formalisms. The outcomes of the modeling effort are analyzed to determine the repeatability of the process. Early results are quite encouraging. Very repeatable results are obtained for three product evolutions, including a toaster, a power screwdriver, and a toy dart gun. In addition, weaknesses in current formalisms are uncovered, pointing to new directions for advancing the field and for carrying out more advanced experimentation.