A communications system may include data storage devices and mobile wireless communications devices for accessing the data storage devices, each using one or more different operating protocols. The system may further include a protocol interface device, which may include a protocol engine module for communicating with the data storage devices using respective operating protocols, and a front-end proxy module coupled to the protocol engine module. The front-end proxy module may include a respective proxy module for communicating with the mobile wireless communications devices using each different operating protocol, and at least one common core service module coupled to the proxy modules. The protocol interface device may also include a configuration file module coupled to the front-end proxy module for storing a plurality of different sets of configuration files relating to different allocations of resources of the at least one common core service module.