The radio used to transmit the data between nodes is one of the crucial parts of the system. As mentioned in the Lessons learned, the NRF23L01 or RFM75 was a good candidate, but eventually failed to meet the needs, so I chose the RFM69. Truth be told, I believe the perfect radio is a combination between the two and some bonuses.

More info at http://www.electrobob.com/1000-1000-hardware/