You cannot go beyond meter scale on export (1BU = 1m). Once I was thinking of a free scale Factor. Maybe I'll implement it, when I find the time and it won't be high priority...
Yeah, I use imperial but it's no big. I just have to set and apply the scale to all of the meshes then set and apply the scale to the armature. So it works that way. It's a bit annoying but workable.