"As a Lutheran, I would not even think of going to communion at an Orthodox or Roman Catholic church. To do so promotes false unity and can only confuse the members of each group. The only possible reason to think of that is a end of life position where there is not time to find my own pastor, and even then it is not something I would personally feel comfortable with."
You've hit the nail on the head, precisely, my friend. And in so doing you can offend no one! The time may come, God willing, when we all believe the same things and there will be a reunion, but until then, intercommunion, except in extremis, promotes confusion and a false unity. We've been down that road before and it leads nowhere.
I pray for Reunion, but until that day it would be wrong to pretend.