This is what got me thinking of downsizing on the length. I think because of a great draft, this Summit cranks even when I have the air cut all the way back. It's not a matter of getting more BTU out of each load, it's almost the opposite. It's about balancing burn time with sufficient BTU. If there's not much noticeable difference in burn time between 18" and 16", I'd rather see less BTU per load, which still keeps the house plenty warm even when we're hovering 0 degrees.
