Roguedent,
If the system relies on the imprest holder to collect and chase up receipts, then yes, it will be a royal pain in the a$$. But if it's left to individuals to keep their own receipts and input their claims on JPA, then the workload will be no less for the imprest holder than it already is ? Give out the money, record it on the balance sheet, hand it back in at home base.
I know my first post gave a defence for the system, but I do feel that this is not the kind of crap we need to be worrying about down route. If a member of my crew loses a receipt, I don't want them worrying about their accountability and the chance of being investigated for fraud whilst operating on the next sector. But I'm afraid that is what's going to happen . . .