Exporting from SSRS to EXCEL is not as seamless as one would hope. I've run into a few issues that have been spicing up my life.
- The EXCEL renderer has a footer limitation of 255 characters. So any nifty footer on the report with instructions and such most likely will not get exported.
- Some web safe colors don't export properly. For instance Pink (#FFCCFF) exports as Yellow (#FFFFCC).
- In some cases tables and textboxes don't play nice and even when sized to the same size through properties EXCEL will throw in an extra zero-lengthed column or three. Fortunately this little goodness is a always favorite to the end-user.
Oh, well... can't win them all.