Stereo vs Mono

Will this outdoor set up https://ibb.co/yhgZmq6   work OK for Stereo if playing all 4 speaker at the same time? or should I set the system to Mono?  Both pairs of speakers will run off its own Sonos Amp so i can set them to either stereo or mono in the app, group them to play together, or choose to play off one set at a time.  I will also be hooking one pair up to an outdoor projector. 
Thanks for any insight.