Distributed Flexible AC Transmission Systems (D-FACTS) and D-FACTS allocation are new topics that are gaining traction in the field of power systems. The reason for this is that they are a simple yet effective tool for improving power flow control, power system flexibility, and reducing overall power systems cost by manipulating some properties of the transmission lines on which they are installed. So far, most research has focused on improving the algorithms used to optimally allocate the D-FACTS along existing networks in order to maximize or minimize a certain objective. However, much of this research has been based on the assumption that all the parameters are pre-defined and immutable. The key objective of this study is thus to study how the changing of different parameters may affect the final solutions found by the optimization algorithm. The key parameters studied are the line reactance adjustment limit, the number of lines on which D-FACTS are allowed, and the investment cost limit. Results show that all these parameters have an effect on the final solution set, and decisions need to be made by carefully weighing the available resources, convenience for deployment, and the potential benefits that could be brought by utilizing D-FACTS devices.