We implemented MS Excel export first because MS Excel is MUCH more widely used than Open Office Calc.
Furthermore Open Office Calc is also able to open MS Excel files.
MS Excel, in turn, isn't able to open ODF spreadsheets.
We are very pragmatic in our support of closed techniques, if it benefits the users.
Since there is no complicated formatting, or formulafields or something like that in the export - i don't really see a big problem here.
Before we add too many Exportfilters , we need to add a "export" button to the interface, that expands when hovered - to show the export options available.
Else we would add unnecessary clutter to the UI, when there are more than 2-3 export buttons visible at once.
Last night i implemented exporting all the files in a Project to a ZIP Archive file.
.Tar.Gz export may or may not follow suit, as linux users can use ZIP Archives too
