This setup is way too town sided. The GS allows what normally are NL MYLO's to become double free lynch days. The gun also makes it impossible for the mafia to cc cop, a job which now falls to the poli. The mafia depend on the poli too much, if he decides to side with town then the mafia are screwed.
As the setup seems to be designed around the GS/Poli though, to balance the setup I would either replace the BG with a leader or agent to keep a unique role and/or replace jan with a spy to allow poli-mafia coordination be better. Replacing a blue with miller would also be good regardless.