Nice discussion all around. The gain in the ubitx is nicely arranged.
Usually the RF attenuator function in the most sophisticated HF receivers is a maual conrol. Since the ubitx does not use a presmp, I don't require an RF attenuation control.
A radio operator csn adjust also the audio gain. But a little AGC can help here.
The LED/LDR circuit appears to act slightly logarithmic which is useful. It works pleasantly with the ubitx gain distribution.
A lossy attenuator network at the front of the ubitx would be a bad thing at high part of HF. An experimentor should evaluate sensitivity on 28 Mhz with and without it. Meanehile, leave it out if you don't need it.