What complications could arise from storing spreadsheets in a database as XML?

XML-stored spreadsheets are limited in support for features such as conditional formatting.

The database-stored spreadsheet setting is unsupported for the complexity of certain spreadsheets.

Extentech advises you to store spreadsheets in their native format in the file system, as a way to allows for retaining the ability for Sheetster to handle any type of input complexity that is uploaded.