Transhumanism gets way creepier than just replacing the body with machinery. Transgenics is also something that's being considered. This goes back to the desire to create super soldiers with the ability to see in the dark, have animal-like ability to hear and smell, etc.
One documentary I watched on transhumanism indicated that just about any form could be possible through genetic manipulation. One of the examples it showed as a possible future human form were centaurs. It was really quite creepy.
Also there will be tremendous pressure put upon people to genetically modify their children because their kids will come home from school upset that everyone else is going to live longer than them, is better at sports, is smarter, etc.
I would still suggest against accepting any of these so-called upgrades genetically.