I've been increasingly using friendfeed, and the number of my subscriptions has trended steadily down. The reason: ordering by time forces me to be strict in who I let in.
Every new watering hole for conversation — facebook, google reader, twitter, friendfeed — orders my reading by time to provide immediacy. Ordering by time renders it susceptible to frequent posters. The minute I subscribe to one, the diversity of my reading goes down. Other voices become hard to find. My response to this: never subscribe to frequent posters.
But this is a blunt heuristic. High-volume sources often have great posts. As the need for other views grows, I find coping mechanisms. Sometimes I give up and leave. Sometimes I build a replacement, and sometimes I find others have done so. Once I can get around pure time ordering, I heave a sigh of relief and subscribe to the people I want to without feeling constrained by volume.
So, friendfeed, please help me navigate this stage of my reading. Find ways to keep my reading diverse, even if I subscribe to Robert Scoble.