I’ve been thinking about how “favourites syncing” might be accomplished. Here are my thoughts.
DVR
On initial installation: Pull favourites from the tuner. Allow the user to subsequently alter them on the DVR. Provide a button to re-sync with the tuner.
Clients
On initial installation: Allow choice of syncing with DVR (if available) or tuner. Allow local alterations. Button to allow re-syncing with DVR (if available) or tuner.
Advantages
Easy to propagate mass changes, as when SD’s Premium TV showed up. Easy DVR and per-client customization. All the flexibility one could want?
Multi-Tuner Situations
This gets complicated. Best thing I could come up with would be great for tech, math and logic geeks, maybe not so much for others: Boolean logic options AND and OR.
When syncing to multiple tuners (DVR or apps): Allow user to select one tuner, or ANDing or ORing from all of them. A logical AND says "set as Favourite only if it’s a Favourite on all tuners. A logical OR says "set as a Favourite if it’s a Favourite on any tuner.
Really Cool Additional Option?
When a DVR is present, allow Favourites to be saved to a Named Favourites Set on the DVR, where it can be retrieved, by name, by other clients 
(Maybe use the device’s name as the default name?)
ETA (to clarify)
By “Favourites” I meant to include “Ignored” channels, as well.