As Doug said, PB Enterprise's main distinction is the ability to capture graphics in addition to the text.

May not sound like a big deal, but it is. Without this feature you need to redesign in PB all the grid lines, boxes, shading, etc. on each of your Adagio forms. Can be quite time consuming if you've got more than one form. I'd bet it's cheaper for the client to just get Enterprise than to get Standard and have all the specs redesigned.

If you're looking at PB for any type of OE or QI form distribution, I'd say that the Enterprise version is a must.