I never worked on Gemini units, but from my experience I agree with not using solder paste without a stencil. Trying it without stencil only needs much more time applying the paste and then for cleaning up the mess afterwards without any advantage. For small pitch ICs like the approx 25mil SSOP of the FT232 I think drag soldering is the most efficient if not the only possible way of hand soldering. For larger pitch packages like 50mil TQFP or SOIC however I reverted to soldering pin by pin using 0.5mm solder and a cheap stereo microscope or strong glasses. This way with a bit of practice no addl flux and no solder wick is needed. The big advantage is that no significant amount of flux gets underneath the package where it is almost impossible to remove by simlply cleaning with IPA. As some flux residue are becoming hygroscopic over time, having no flux residue on a PCB can be a big advantage if the PCB is used in humid air / outside. I'm not sure whether this is relevant to Gemini units at all, but for battery powered sensors for example flux residue becoming moist can increase sleep current considerably and significantly shorten battery life. Went through this myself...
?
Regards,
Stephan
