In order to perform daily maintenance and repair tasks in complex electrical and mechanical systems, technicians commonly utilize a large number of diagrams and documents detailing system properties in both electronic and print formats. In electronic document views, users typically are only provided with traditional pan and zoom features; however, recent advances in information visualization and illustrative rendering styles should allow users to analyze documents in a more timely and accurate fashion. In this paper, we evaluate the effectiveness of rendering techniques focusing on methods of document/diagram highlighting, distortion, and navigation while preserving contextual information between related diagrams. We utilize our previously developed interactive visualization system (SDViz) for technical diagrams for a series of quantitative studies and an in-field evaluation of the system in terms of usability and usefulness. In the quantitative studies, subjects perform small tasks that are similar to actual maintenance work while using tools provided by our system. First, the effects of highlighting within a diagram and between multiple diagrams are evaluated. Second, we analyze the value of preserving highlighting as well as spatial information when switching between related diagrams, and then we present the effectiveness of distortion within a diagram. Finally, we discuss a field study of the system and report the results of our findings.