The Architecture of Integrated Information Systems (ARIS) is a popular framework for integrated process modeling. Previous research analysed ARIS using an ontology developed by Bunge, Wand and Weber. The results of this study have been summarized in six propositions. This paper reports on insights gained from an empirical study testing these evaluative propositions. The study is conducted with post-graduate students as well as with experienced users of ARIS. Even when considering all five views of ARIS, modelers have problems representing business rules and the scope and boundary of systems. Surprisingly, even though it is completely ontologically redundant, users still find the function view useful in modeling.