Yes, but in the same time the RSSI is affected also by strong interferences as, Adjacent Channel, Inband Blocking, Cochannel Interferer, etc.
So, probably the best channel estimation is to do a combination of both, BER and RSSI, where BER is proportional with SNR.
In your Noise Floor formula you forgot to add the gain.
Noise Floor[dBm] = – 174 + 10*LOG BW[Hz] + Noise Figure[dB] + Gain[dB]
Strong interferer could saturate the front-end, and raising in this way the overall noise floor.