Hi Edward
I would not vote in favor of live updating of Inventory from Invoices. If they want that, have them use OrderEntry, especially now that automatic invoicing of orders is coming along in the next version.
I have clients who do their billing in various Invoices datasets so they can have multiple invoice number series and better security, and then import the ICSBATCH file into a master Inventory dataset, which also has Payables, PurchaseOrders and Ledger. I consider that to be a positive, not a negative.
But try to convince me why this client needs to use Invoices rather than a combination of SalesCQ (to do quotes or work orders) and OrderEntry.
Steve