Facing the same issues:

1. Adding barcodes t existing inventory.  Very large items among the list that are impracticvle to lug a laptop to.  Want to scan them into a device and then do a batch (like) update to items in QB.
2. When invoicing, a customr is in a service area, but s/he may have purchased items from the warehouse that go to the loading dock, but invoice is created in the service area.
3. Even if the items are with the customer in the service area, the scanner is not going to be used next to a desktop but out in front of the counter.  We need to control the invoicing from the scanner (advancing to next line, adding quantity). 

A smart scanner is necessary.  Does the MC-40 do any of  that?  Does the Android phone app do it?