It can somewhat be customized but this is really not the market they should be installing in. Multiple audio zones can be joined/grouped and adjust volume via the zones page but full customization of the UI is not possible. Handing multiple video zones is less easy and not as intuitive as you would have with a fully customized UI. I think if this was an audio only gig, C4 would be ok. But introducing multiple video zones, swapping between them, joining and syncing them up with audio can be cumbersome. There are some third party drivers that may assist with this but I am not all that familiar with them. IMO C4 belongs and does quite well with residential or hotel/MDU but not all that well in commercial gigs like bars.