I don't really see why it has to be a 7-v-8 conflict. Both styles can be used on the same startup with minimal disruption.
Just pop up the win7 menu and attach the win10 version. All you lose in from the Win10 point of view is one column of quick links. The All Programs contains the programs list, and you still get the space for tiles, if you want. If not, just close the tiles by collapsing them horizontally (so they don't appear)
Very crude mock:
