Just a few quick thoughts...
Clients have their own independent osd. Clients have their own display and audio settings. Clients detect disconnect-from-server and attempt reconnect. Client labels (living room, office, kids, man cave, etc) for easy maintenance & identification.
Servers able to (dis)allow timer privileges (create, modify, delete) for each client. Servers able to (dis)allow recording privileges (edit, delete) for each client. Servers able to handle multiple clients that may be trying to modify/edit things such as timers & recordings. Servers should have smart device selection. For example if dvb-s is requested, use an available dvb-s device before dvb-s2. If a non-turbo fec device is requested, use an available non-turbo fec device before one that supports turbo fec. Or some method by which users can create their own device priority list.