I tested the initial Moblin releases, wich were based in XFCE, and was very pleased with it. Should I be able to replace the fancy Moblin UI with XFCE again, I would be happy as a child.
On a second thought, maybe my wife (the real main user of my netbook machine) would like the Moblin UI best, as it fits better what she does with the machine, so being able to chose UI would be best, IMNSHO.