Hi Bjørn
That's excellent to hear, yes the nRF52 can be an excellent candidate as an application MCU as it's currently one of the most energy efficient Cortex M4 based MCUs out there. Further the nRF52s BLE capability can come in handy for near Node communication (set up and debug++).
As for mbed I believe that is the way to go if we want to leverage ongoing activities around the world.
https://developer.mbed.org/blog/entry/Swisscom-Hackathon-Wrapup/
-Thomas