What about long-term stability?

To be sure of hearing a weak SSB/CW signal, the receiver needs to be within about 1kHz of the transmitted frequency. JT44 requires about 200Hz mutual accuracy.
At 148GHz that’s about 1 part in 108 for SSB/CW and about 1 part in 2.109 for JT44
Even at 10GHz we need about 1 part in 107 to consistently find an ssb signal.

To be sure of hearing a weak SSB/CW signal, the receiver needs to be within about 1kHz of the transmitted frequency. JT44 requires about 200Hz mutual accuracy.