As n00bl3t pointed out the mines on the vessel are generally more of a liability in most kinds of combat. Especially against bombers. I've fought many Junkers flying this ship and, most generally, it involves at least one sequence of hilarity where the pilot flies in desperate circles nuke mining himself into oblivion while I calmly CD him, waiting for the next SNAC shot.
I personally feel that the Zoners could employ Explorers should they require something with a little more firepower, not that there is a lack of Zoners already flying the Order Gunboat, but Mal's point to the Conference's specs not being up to pay is dead on in my humble estimation. The thing needs more cargo if it's going to pass itself off as useful, let alone its intended role. The Rogue gunboat is many times deadlier and barely take a comparable hit.