I'd say a major issue is editing this different emotional and tempo based shots together... And then eventually rewriting that full score to chase the singers tempo on set...
A hugely ballsy, fun nightmare!
Europa Sound & Vision
Euphonix 32 fader S5MC + stand alone MC, Nuendo x 7, Protools x 7
Dub stage with HD projection (13m throw), VVTR,
and soon a complete picture department with online, grading and more. http://www.europasoundvision.se