Pictures are worth a thousand words. If you can create a photo montage of the gear and how it's deployed, many engineers can come up with a rough idea of what it is going to sound like in much better detail than a list of specs. Of course, having both on hand wouldn't be a horrible thing to have, but if I were given the choice of seeing a vague spec list or detailed pictures, I'd take the pictures any day. Seeing pictures can tell you a lot about how a system was deployed, even more so than just a list of gear and a loudness spec at some random measured point in the room.