Hi @davidmatyas whilst you can export out the lists to IIF format you cant do that for transactions other than for journal entries from inside QuickBooks desktop.  

There is another option but you need to use a third party data import and export solution.  One that I pulbish is called Zed Axis - you can use it to export out transactions from QuickBooks desktop to Excel and then use that data to import into another QuickBooks company file.  There is a 30 day free trial you can download from the Intuit Marketplace.