I've got your overarching point. I reacted to your (rhetorical?) question and pointed out that humanism and morality in general are indeed linked to hard facts such as universal causality, lack of universal objective values, human behavioral and cognitive patterns, etc.
As for your question -- first, I'd also like to add psychology (neurobiology is a given) to the list of those areas that deal with subjective values as it's perhaps the most important field that directly tests what's up in that regard (in Europe we don't have such drastic problem with replication as it's present, from my viewpoint, overseas ). Then the questions can be simply reframed -- do you want to live in pain?
As I see it, nowadays, the most cutting-edge but also the most naive answer to this question is transhumanism. However, it is the case only because transhumanism is not rigorous enough and thus it's rather shortsighted. After all, has any transhumanist asked how will a life spanning several centuries influence human psyche and those illusory subjective values you talk about? My guess is that it won't be a pleasant enterprise. I also shudder at the thought of a copy of my mind in a computer as we know them today. Poor my copy (or copy-me? :D).
Of course, there are then the rather obvious objections that why in the world I should work toward anything or for anyone and not act simply for the heck of it and let the rest freely follow. And most importantly, how can you even question equality when everything is objectively equally valueless, or from a different angle, equally priceless?
And just as a side note, I have always considered philosophy to be a science and science to be a form of art. After all, art is merely a level of mastery and science a level of meticulousness. In theory (but also in praxis) you can even bake bread with scientific rigour and artistic skill.
Anyway, since everything is objectively leveled, technically, you are free to live in pain to the extent that you don't spread that pain to people who prefer to live in a different way. Likewise, one should not disturb a natural masochist with pleasure. Then again, even a masochist just uses pain to derive pleasure from it. Well, in the end, it is indeed really simple.
