Good timing with your question. Over the last few days I took some 'crude' measurements. It depends on which operating system you are running!.
Android idle ~0.6Watts
Linux (Ubuntu 15.09 release) idle ~1.3 Watts
Linux loaded ~4 Watts using "stress -c 4 -i 4 -m 2 &"
I measured these values by putting an ammeter in series with the DC power jack, taking the current reading (in amps) and multiplying by 12 (volts) to the consumption in Watts. The Ammeter readings are not very stable (because the power draw is constantly changing as the system does things), so the measurements are not very accurate, just me averaging the readings in my head.
I strongly suggest you measure your own power consumption using your peripherals and applications. The 'idle' numbers are with the display running and active, this is not a sleep power which obviously could be much lower.
Warning!: these numbers and are affected by many variables. I had bunch of stuff attached to the 410c, a HDMI display (it does draw power, but I haven't measured how much), a mouse and keyboard (again how much power do they draw?), a 64GB SDCard as swap space, and a 96Boards Arduino mezzanine board (more power). The software obviously makes a huge difference as you can see by comparing the Android and Ubuntu idle numbers.
I am working on an app note on how to measure power which I hope to publish in the new year. Since the SW mates such a huge difference to the system level power, I think it will really help the developers if they can easily check that their changes don't increase power consumption.
Full Disclosure: I am an employee of Qualcomm Canada. Any opinions expressed in this post or any other post may not reflect the opinions of my employer.