Amy0406:
The Nano is only slightly larger than the mini yet, from my point of view, the mini looks much harder to set up and is less documented...
This is not really right. Amongst all as described above, a fundamental difference between Pro Mini and Nano that the former requires conditioned power and programming through a USB adapter, while you can just plug a USB cable into a nano, just like Uno. This means Nano is 5v only.
An important consideration is that, by virtue of those NRF24s, you are clearly interested in remote operations. So note that Pro Mini is available in a 3.3v version and therefore eminently more suitable for running off batteries. The NRF is also 3.3v - which rather simplifies matters.
You might find Pro Mini worth the little extra effort.