This raises some questions:
1) At what angle would I cut to achieve the profile for the cope? For 90 degree inside corners, it's 45 degrees.
2) The back cut with the coping saw would have to be at a very extreme angle. Would this make it much more difficult?
3) Should the non-coped ends also be cut at a slight angle so they meet the wall flush?
4) Would normal mitering be a better option than coping these joints? If so, any advice on getting the measurements right? Also, I'm sure the actual angles will be off by a degree or two -- would it be worth it trying to cut the exact angles?