just do it
x-reality just oversaturates colours and drains battery to process every image, i find i like images with it off.
the z2 has a fantastic display and colour range without x-reality
DRM keys never used any of the sony content in my life, infact i rooted and first things i removed was sony social and 'whats new app' which just run in the background drianing battery and probably monitoring your usage to send ads...
Mirorr linking is one of those cool, but probably never use/ use once in a blue moon type feautre.
Unlock that boot loader, root it and start modifying the phone to your taste ( the main point of getting android?)
You lose nothing vital