Also, humanity-wise, I.e. still considering the augmented entity to be still human is the relative ease to UNDO, the change. If a modification is permanent, i.e. un-undo-able, or very hard to undo ... it definitely presses the user towards the without of the human-ness domain. It is like the genetic modification - it's been considered as something which is done before conception and for life ... but indeed reversibility would make even the most radical genetic human alteration to be as 'mutating' as glasses or clothing. SO, the actual implementation and application of body/mind augmentation and boosting tech will be subject of competition. The 'bang for the buck' criterion.