Interestingly it's like the same goal from different ends. Banyan is targetting per-user aggregation model, but it will whittle down that user set pretty aggressively. I don't know what that number will be but it will likely land in the low hundreds. About the size of your average follow list, and that becomes an auto-whitelist and shifts around over time.
On that foundation, it would be cool to let those people make custom feeds based on what they want to see from the curated set of events that get collected into the relay.