If you dont change all the shitty conventions and rules of an antagonistic system pr wouldn't work.
Parliament could be collabatory or Investigatory even with fptp but we choose not to be. Pr changes the way governments are formed not necessarily how parliament operates (winners Vs losers)
You would find that extremists on the left and right would end up with an MP or two.
I'd rather see an change in our antagonistic parliamentary and legal systems before a change in fptp.