I'm on Team Pannier for now, but when I get my first road bike, I'll consider a Carradice saddlebag for carrying my work clothes, and use my current bike for the grocery runs and commuting on days that I think I might want to stop by the grocery.

I was also thinking about getting a Fly6 rear-facing camera/tail-light, but it mounts on the seatpost, which is where the Carradice would go too - I'd have to decide which I'd value more....