<i>“If you had to pick an optimal human to machine cyborg ratio, what would it be and why?”</i><p>[looks at self] Being one, I'm not quite sure how one computes that ratio.<p>What's more important is how the mix leverages one's self to an advantage. I can't engage in certain activities lest I risk terminal disconnection of electromechanical components ... but installation of those same components prevented early cessation of the wholly 100% human configuration, and at least once since have, by happenstance, made the difference between racing to the ER by ambulance vs. walking in at my convenience and tolerating pre-surgery delays. The ability to do periodic data dumps on biosystem performance has also been everything from amusing to critical.<p>At this point of technology, I wouldn't recommend purely voluntary installation of machine parts, but if there's a good reason to get them then embrace the options fully.<p>BTW: battery replacement sucks. Yes, it's done the hard way. No, wireless/inductive recharging isn't reliable/durable enough to be viable.