Some suggestions for SCC basic/Pro (I have not been able to check if paypal or google checkout provide any of these)
Will there be an ability to email an order acknowledgement and/or a despatch note/ invoice.
Ability to use an order ref number and/or invoice number.
Any thoughts on creating a transaction file with product, qty, value, order/inv ref,date,total order value etc. This would very useful for an audit trail.
Perhaps somehow it would possible to copy this transaction file to a spreadsheet for sales analysis.
In he Uk many online shops email a confirmation of order and then email an invoice on despatch of goods.