I understood your thinking to be: some things are possible and desirable; other things just aren't possible; transhumanism wants the impossible, such as physical immortality, superintelligence, mind uploading, and nanotechnological abundance. That is a maximalist agenda for transhumanism. There's no denying that the extremes get the attention, both inside and outside the subculture.
What you are describing as "minimalism versus maximalism" looks to me more like research versus wish-fulfillment fantasizing, sanity versus incoherence, science versus religion. Robot Cultists like to frame their confusions of science fiction with science fact as a kind of "daring" on their part, they like to fancy themselves visionaries or what seems more like jocks of science by handwaving about superintellinge, superlongevity, and superabundance rather than consensus science. I do not agree. I think they are just engaging in a kind of advertising and promotional discourse unconnected with actual research, advertising in a hyperbolic mode that has many of the hallmarks of outright fraud.
I also think techno-transcendentalizing futurologies like transhumanism indulge in something that looks quite a bit like evangelical religiosity in its least pleasant most dangerous crusading and promotional modes. Although I am not at all a religious person myself, I don't disdain religious expression in others any more than I do aesthetic expression in others (there are lots of paths to meaningful existence). But I do insist we all take great care to discern and distinguish and criticize religion (or for that matter aesthetics) whenever it seeks to colonize, distort, or be mistaken for science or proper politics. That is as true for Pentecostals or Muslims or Mormons as it is for Robot Cultists, in my view. When an sf fandom or PR firm (every futurist is essentially a salesman) confuses itself for a policy think-tank or social movement, enormous mischief ensues.
Although I do indeed think immortality and nanoabundance and mind uploading are practically impossible, this is not -- as it is usually framed by Robot Cultists -- a matter of my quibbling with them about developmental timescales or lacking their "can-do" spirit or ability to "think big." I don't confuse lies with optimism or incoherence with bigness like futurologists characteristically do.
More to the point: I think "mind uploading" involves deep confusions about what intelligence (which is embodied and social) means, what personal lifespan (which is also embodied, social and inherently, indispensably vulnerable) means, or what it really means to aspire to post-political superabundance in terms of lived human freedom (which depends in its substance on plurality and contestation). I don't think transhumanists want "more" -- I think transhumanists literally don't know what the hell they are talking about, and that when they talk they are deranging public discourse in a way the public is disastrously susceptible to in a time of disruptive technoscientific change and global corporate-militarist developmental precarization.
I frankly don't think transhumanists are ultimately saying anything that any hungry bored lonely infant in a poopy diaper isn't already squealing about in his crib. You just trump up your infantile wish-fulfillment fantasies in the trappings of science fiction iconography and appeal to a slightly more hyperbolic id than do the usual run of the mill consumer-capitalist sports car and boner pill ads. That you people seem to think this represents a philosophical worldview or cutting edge science policy is nothing short of flabbergasting in my view.