Hi, my 5s is almost 4 years old and it is too small now so a replacement is needed. I wanted to try the Xr but it is too big and heavy. So I'm leaning to the iphone 8. It is worth it in 2018 for 685 euro or should I look for another option? About the color, I always want a black front and a white back. Should I pick the space grey then use a white back skin? Never used it before so which site is good ( dbrand, slickwrap...?) How long does it last? I guess the back is detachable without much problem, beside warranty? So should I go to a third party to ask them to change it for me? Has anyone did this before?