Do you understand the rear elevation at the 3 French doors that he drew? Has he drawn a cut section through the room? Has he given you interior elevations of the room? It's a very good solution. If he doesn't cut in the EW vault like he did, then even with the high ceiling in the Family Room, you would end up with low glass, because your visual is limited to the bearing line out at the edge of the patio. Ask him to find a photo for you on Houzz before you spend $1000+ on a 3-D