I do not think there is a Princess Wu. (think HostasDirect had a typo. Sent a e-mail to the owner alerting him of the possible error earlier this late winter).
YES, Xanadu Empress Wu is the same as Empress Wu. While the Xanadu was dropped probably for marketability I also suspect it was dropped due to cultural conflict as well. "Xanadu" is Greek mythology and Empress Wu is Chinese history (only female EMPEROR [not Empress] of China).
It was good to get information about XEW growth rate for it maturing in 6 years. Purchased 3 of them from HostasDirect late last summer and they took off growing like gangbusters. (tries to look innocent; maybe it had to do something with sheep shit). Looking forward to seeing if they come up (there's gotta be one in three chance).
Peter Kelley
St. Paul, MN USA