This would seem to have huge implications if running off two alkaline AA cells, which is what's shown in the photo on the OP of this thread: looking at constant current discharge curves of alkaline AA cells, a significant fraction of the useful life of the battery happens below 1.2v.
So, just to be clear, in your guys judgment based on the RF switch part, we shouldn't be running below 2.4v as far as the RFM69 radio is concerned?
[Edit: Ultimate Lithium AA L91's are a different story. They would still seem to be a perfect fit, as most of their useful life happens at greater than 1.2v.]