Ok, I usually do not look like a tool and wear all these gadgets at the same time. When I run outside I usually go with my Garmin 305 and Fitbit. Garmin for my distance and pace. Fitbit for tracking my steps. Calories on my Fitbit and my Polar never match up. I trust my Polar over my Fitbit, ALWAYS, since my Polar is actually monitoring my heart beat with the chest strap.
I'm not concerned with calories burned or my heart rate when I run outside since I usually run at an enjoyable pace and socialize with friend as I go. I am not pressed for time or needing to hit a certain number. So I leave my Polar at home. I use my Polar for lifting workouts. I like my Garmin outside for distance and pace and it's fun to hit my 10,000 with my Fitbit in the first part of my day.
I made sure to start all gadgets at the same time and as you can see, the miles/distance were fairly close with the Polar and the Fitbit. The calories burned on my Fitbit was 716 MORE than what my Polar said.
Now that I am done with the run, I will take off my Garmin and my Polar. I will continue to wear the Fitbit because now that I have hit my 10,000 it is actually really fun to see how many more steps I can get in by the end of the day. The Fitbit is fun and motivating in that way.