Apropos of the Gan debate (which I haven't been reading so apologies if this is repetition), it occurs to me that there's very little real evidence for Gan being any less intelligent than the average of the Liberator crew, excluding Avon and Orac (at least if you take at face value people/AI's opinions of their intellect).
We see him in a mere 17 episodes, mostly in a background role. During which time, he acts as a de facto leader at least twice (Space Fall, Cygnus Alpha), he takes a stand against Blake's decisions (Shadow), he learns to pilot Liberator, he takes a technical role in its maintenance (Redemption), he's shown learning from Orac and being lectured to by Avon (about the auto-repair mechanism). [Sorry some of my memory is faulty as to episode.]
I actually see the incident where he's learning from Orac as being quite important to establishing his character -- yes perhaps he's less well educated than some of the other crew members, but he's willing and able to learn as an adult, which IMO correlates with intelligence.
I wonder if there isn't a bit of a perception bias here. We have Gan the 'gentle and slow giant' to go with Blake the 'hero', Avon the 'genius' and Vila the 'cunning thief'. Size isn't the only metric.
Tavia