Yep! I'm talking rampant transhumanism again. There are a lot of games out there that assume or promote Transhumanism. Like all "*isms", it creates "*ists" - thanks, Brad! - meaning it becomes a philosphical/political/religious party in effect, with consequent followers, ideology, and ideologues. I have no problem with basic Transhuman concepts - that technology will enable modification of humans into many, many different shapes and forms, and even formats - as machine intelligences are no longer a biological format at all.
As a writer of SF RPGs, it is not only probably practical - far more so than FTL travel, for example - but it makes for engaging RPG play. I have built many a campaign on the meaning of the word "human" in one way or another; robot characters, designer species, radically morphed bodies, etcetera - are they human? Should they be treated as humans legally? Morally? Ethically? Is slavery of another species wrong? What is slavery when applied to non-baseline humans? How will people treat radical morphs? Lots of great RPG fodder there!
So does that make me a Transhumanist? No. That is an ideological position, and like all ideologues, Transhumanist ideologues assume that everyone is really like them. They assume that given the choice, the bulk of humanity would choose radical physical change. I disagree with that position. I think that given the choice, the vast majority of humans will opt to be smarter, fitter, and sexier humans. Only a small percentage will opt for radical physical change, especially radical *visible* change.
Why? Basic human wiring. Most humans prefer the company of people pretty much like themselves. They may find other shapes interesting, even pretty, but not mate-material, and mating is a basic human condition. Look at how long it took us to even consider people of other races of humans as mate-material! People who diverge too much from the standard human plan would be a different species, and different species are not for mating - for perpetuating the line, for having children. First of all, they may be too far from the norm to produce viable offspring. Second, any such offspring would of necessity be like both parents, and thus consided a freak from both sides. Sexual selection would push towards the mean, to the human baseline and away from the edges.
On the other side of the question, even that small proportion of humanity that would love to take radicallly different forms could not possibly agree on a single form. Each would be sexually isolated from the others as well as from baseline humanity, and they woudl be in far smaller numbers. The proportion of neophiles to neophobes in humanity is very small, and while anyone who would want to radically change away from the humaniform plan would by definition be a neophile, not all neophiles would want to change this way.
I would expect any human society capable of Transhuman transfiguaration to be structured as a huge clump of baseline humans, with that baseline significantly higher than our current baseline, with a smaller envelope of somewhat different - but not too different - almost baselines. Outside that there would be a fringe of radical neo-morphs, mostly singles and one-offs, and finally small clumps of successful designs who had enough "subscribers" to make a viable population, mostly those designed for colonizing worlds not viable - either economically or physically - for terraforming.
As for changing to other formats, I don't really think that's viable. I think Machine Intelligences will be designed as MIs, whether robotic or discorporate, not humans who were scanned and "uploaded". Scanning on a level sufficient to reconstitute a whole persona would of necessity be totally destructive and probably, by the nature of being machines, not really very human at the end of it all. Voluntarily choosing to be discorporated and reconstituted in another form requires one to effectively be suicidal, with no guarantee that the other form is really a continuation in any way of what is really you. It is effectively death and a possible afterlife, and thus a matter of religion, not science.