Software Product Lines are intended to reduce time to market, improve quality and decrease costs. In this paper we examine the evolution of a single system to a Software Product Line, and evaluate if these benefits have occurred in this case. We describe in detail how this evolution took place and relate our experiences to those described in the current literature. Three tenets used by the company involved helped avoid some of the known pitfalls. A configurable core asset version of functionality is compared to the previous customizable version of the same functionality. From analyzing empirical data collected over a ten-year period, we find that efficiency and quality have improved, while costs have been reduced. The high initial investment associated with evolving to an SPL has been postponed by taking small steps towards an SPL architecture. In addition, this approach has enabled us to expand our product into a wider market and deal with more complex customer requirements without incurring a corresponding increase in staffing and costs.