Well, I returned the HF one and got a Dewalt DCK281D2 20v combo package from Lowes. I'm still trying not to think about the $$ difference.
As for usage. I finished my project and drove about 120 screws into the cement backer board into 2x4 studs all on one battery. The batteries on-board monitor even said that it was still fully charged. That made my work go so quickly it was "almost" fun.