Don - KM4UDX
As a uBITX devotee, I can report that the SSB home brew is "uBITX adjacent". The SI5153, the arduino, dual purpose architecture, IFR510 final, etc all parallel the uBITX. And Dean's Furlough 40/20 has scored numerious QSO's with other uBITX operators.
I'd like to think that is some way, the uBITX gave way to the F40/20. A more primal primitive offspring.
The uBITX got me into the radio hobby. It was approachable, reasonable, wickedly capable, and CAT-enabled.
But mostly, and I did not appreciate this when I started, it had a vigorous supporting ecosystem. Having a group of smart and kind folks to answer the same questions with grace, and point out the obvious to a newbie, was actually the key secret ingredient. The uBITX and tribe was a perfect gateway drug.
The SSB F40/20 is now helping me learn how these darn mystical miracle devices called radios work. It has the same (if much smaller) supporting environment. And that makes it all work.