I haven't used ARM meaning I didn't make my own ARM board, but several devices that I use everyday are based on ARM processors:
eg. GPS devices, smartphones, etc.
So for me to low power consumption robot solution (instead of using mini-itx boards) was using a smartphone directly. A lot of processing power but also several modules like WLAN, Camera, etc, all for little power consumption and weight.
What I'm saying is that for a robot you can use a smartphone directly, instead of purchasing expensive ARM boards. See Perseus3 in my sig. for an example.