No... I meant Ubuntu Core (this is another OS available for DB410C in addition to the Debian images from Linaro and the AOSP build from Qualcomm.
However, whilst I meant what I said I think perhaps I didn't properly read your post first time round.
This was the bit that confused me: I couldn't understand why Debian would be sized correctly but Ubuntu would not. However I now guess that this was a misinterpretation.