The Brooks B-17 that I got for Christmas seems to be finally broken in and fairly comfortable. It was a struggle and I only rode it for short rides for the first few months. My questions is: Do any of your Brooks devotees use the Brooks matching seat bags. From the photos I've seen, the Challenge bag really looks "cool" but seems like it might be too small to be useful. The Millbrook bag looks like it would be pretty heavy. Have any of you tried these bags?