>>I think, if you don't specify a type with additional parameter in SaveAs, it'll be saved as is w/o converting to XLS. IOW, specifying XLS extension doesn't convert open document to XLS type.
>
>Does the template really have a different format? I know it does in Word (for instance, a document can't include macros, a template can), but I am not so sure in Excel.

I dunno but I prefer to be safe than sorry. :)