In Blend, as soon as you insert a control (like Button) and start dragging it onto Window/Grid/whatever you get hard-coded margins and width/height.
Thus designer that I work with ends up creating beautiful static pictures that, on my side, fall apart as soon as one data-bound string is longer than the sample ones. Or if font size gets increased. Text ends up clipped or otherwise unreadable.
Blends makes it so easy to make rigid, but pretty designs, that I have a hard time selling the need for a more complex design work, using styles and panels, to my designer. By now I see only one option - let design eventually fail at customer's site and have designer learn the lesson from that failure. Of course, it is not a great solution to use customer's bad experience just to educate designer.
What are your experiences and suggestions in this area?