The cool thing about the calories burned and the exercise METS, is that you can clearly see when you metabolism is firing up and what causes that. Since I exercise a lot, it is a good thing to know. In addition Most BMR calculators put my avg cals burned while just sitting around at 2400. The truth is on a lazy day, I actually burn only 2100-2300 cals. Since I do believe calories count in some ways, this information is important to me.
The fitbit did not exist when I got my GWF. I might have considered the FB otherwise, I still consider the $7.00 to be worth the extra perks that I get from my device.
This conversation will be helpful for others who are deciding between the two.