A fully functioning sandboxing environment that is an exact clone of the account it is linked to would be very useful.
As a company we have multiple Kashflow accounts for different currencies. This means that for running unit tests we require separate accounts for sandboxing (so as not to affect live data).
It would be good if there was a simple way to access a sandboxed replica of a Kashflow account. It is definitely something that is missing and will be required by many companies throughout development.