Why do you think 1.2 GHz would be less congested?

Wi-Fi is congested because (1) lots of neighbors, especially in urban areas, and especially on lower bands where the signal penetrates walls better, and (2) unlicensed devices have to tolerate interference from other unlicensed devices, and (3) limited overall spectrum bandwidth, particularly as you go down the spectrum.

1.2 GHz would have all these same problems, but worse by being at a lower band.