Is there any way to export a spreadsheet to raw XML without the table:number-columns-repeated attribute on any cell (and just have them duplicated) ? This attribute is really a pain because, if it weren’t there, it would be very easy with a simple xpath 1.0 expression to fetch the value of a cell. With this kind of “optimization” (and I’m really not sure the compression benefits are there in most cases), it way much wilder to correctly write your XSLT stylesheet either having you introduce variables, functions or multiple templates…
If you are only interested in the values and not in formulas and styles, then you can export to xhtml.