I just got these and noticed that the under the battery cover, there are two slots for (3) batteries each.  I don't know why I tried it, but I thought to click the light on, with only one side filled.  Sure enough, the light came right on!

Tried it on my second sconce thinking it was just a fluke and yep, with only 3-of-6 batteries installed both work like a champ.  When I put the 3-additional batteries in see if maybe the light got brighter something, there was no change.  Score one for the consumer!

Pros: Only takes 3 batteries to power, instead of 6.  Nice soft light output.
Cons: Nothing that I can think of so far.  Sure it's plastic, but I knew that going in.