If capacity is such an issue (which I doubt it is) as well as the branding, then surely each channel could have simply had a static barker channel which would take up minimal capacity each?
I think the real issue here is the costs associated with carriage and maybe Universal music weren't prepared to pay what Virgin wanted and this was an agreed compromise? I always thought was the reason for some channels appearing/disappearing from the MTV portfolio.
Look at World Box - half those channels would never have a chance in hell of being carried by a traditional method and that was seen as a cost effective delivery method.
Just my viewpoint