This is my personal opinion
I dont mind if you kill my char even if my party do bg :) we are playing on opposite factions
since we cant play on a same faction fighting cant be avoided and i hope there will be no drama about being killed by friends
For me fof is a family not a clan of one faction only some family members play forsaken and some play chosen it would be great if we play altogether on a same faction but everyone is free to choosego where he/she will be happy.
Just think of this for example you like miami heat and your brother like oklahoma thunder, even you both like two different teams you are still.brother and sister and a family.