We had both for about 6 months...
It was my ride that my wife used after I received my new X5 E70... Now it is gone and is replaced by a new MB C-class in white with amg-trim
Personally I wouldn't buy the X3 again and actually I bought it very fast second hand when I needed a new ride immediatly... It is in now way comparisable with an X5 and if your wife likes that one I wouldn't give her a X3.
Maybe, if possible, wait for the new model, which will look a lot nicer.