are hive men sentient in the same fashion we are? Do they experience the full range of subjectivity the modern homo sapiens does or was some of that excluded from their creation? It feels like it would have to in order to make them function well in an eusocial context. I'd be curious if you could expand on that
This is a question i've left a bit ambiguous for myself, because there is a wide range of answers.
In one version of the hive mind, a mass of human brains could be linked to become components of one huge brain (like the components of our own brains), with the individual completely subsumed into the whole. This angle is one that I want to play with later, as a biotech answer to making supercomputers...
For our martians, and the crew of the Hale-Bopp dyson Tree, I imagine there would be some of this at play, since my presumed method of communication in the hive is some sort of radio-telepathy - low-fi neural network stuff. Individual hive-men might have some agency of their own, though, in how they reacted to specific stimuli.
But you're right in that their subjective experience would be a lot different then ours, in part because they'd always be sharing in the data from the rest of the hive. There'd be little individual internal life for a hive member, since they'd always be picking up feelings and thoughts from their hive-mates.
In the story i first wanted to make about the hive-men, a big part of it was about an earthman finding himself inducted into the hive, and having the neural biotech grow inside him... and finding that all his individual neuroses, worries, etc, were obliterated as he found the sweet release of ego death, losing himself into the hive. Like when people surrender to a cult, basically, but this cult doesn't have a tyrannical leader, and operates as a super-organism... which to me seems a little more appealing.
Now, because this is science fiction, I like to think that the hive, as a collective mind, would be a bit more sophisticated than an ant colony, and perhaps capable of more abstract thought - daydreaming great symphonies, pondering philosophical and scientific problems with the brain power of the whole hive, that sort of thing. Not just reactive, but pro-active. But the rich, subjective internal life that is the heritage of all humans might not be as useful, or as possible, when you're sharing your thoughts and brainpower with ten thousand other people.
As a final little thought, I do imagine that these hive men would have began as a voluntary experiment by scientist types, somewhere out in the rings of saturn, far from the prying eyes of earth. Perhaps starting as a more traditional cultish organization, to start, but I'd like to think that the practical problems of living as a super-organism in deep space would temper the more extreme elements.
(but another story idea i would like to flesh out, one day, would be the bad side of other hive-people - non-biotech hive cults prone to mass religious mania, etc. There's a lot of room to play in...)