A further data point.... I called the EXP line again and they again confirmed that "U" class is a bucket that has restrictions for Business Extra awards that are different from MileSaaver awards. However, after a one hour and forty-five minute call between the EXP desk and meeting services, they were able to offer me a routing close to what I had wanted. My takeaway here is that it is not safe to assume that the awards are the same, and that status can create some availibility (but not guaranteed).