After creating a beveled hill in Xara, I always use a heavy dose of 'feather object' so the hill blends in with the background. Sometimes I convert the beveled hill to 'convert to editable shape', while I can't alter the bevel any longer, feathering works better, however it feathers both sides of the bevel so you'll need to be careful about revealing the layer beneath the hill between the bevel and the top of hill (I'll place a small extension of the hill top color to place beneath the hill to minimize that issue.) I usually apply such a heavy feather that the hill bevel is barely seen, more subtle and more realistic. Also consider giving your hill transparency level to blend in the background as well.

GP