Let me first thank you for the projects and experience you share with us. I am interested to find out how uBITX behaves in terms of selectivity and sensitivity?
I also support the idea, that if you want to cover all HF band a set of (at least) four LPF for the PA is a must.
Additionally, looking at the uBITX schematic, I couldn't help but notice the bidirectional amps slightly differ form the original idea of W7ZOI and K3NHI. You used different biasing approach, but it appears the input impedance is not 50 ohms. My LTSpice simulations show 90 ohms at 10MHz and 50 ohms at 45MHz. And the "gain" transistor is biased at 15mA. Would you, please, share with us what your idea was for doing these mods.
73 de LZ1NEF