If I remember correctly in one of the Iron hand novels it showed that one of the main drawbacks of becoming more and more bionic is losing your touch with reality and abillity to properly cooperate with other people.
In the novel the Iron Hands are besieging a hive together with several IG regiments and Titans. In the course of the siege there are more and more problems between the Iron Hands and their allies because the Iron Hands can't really understand why the IG don't keep up with their attacks and why they can't endure the same punishment resulting in several critical operations (almost) failing.
But how much of this is due to the bionics and how much is due to the Iron Hands personal philosophies (Flesh is Weak) and general super-human-ness. We`ve seen examples of non-augmented marines having difficulty understanding the limitations of the human body and mind.
"Look into my eyes, and see your death."
"Let them hate, so long as they fear."