One thing that is nice about the iPF series is that, while they have the custom Photoshop plugin, they also have a very well-developed OS driver (I actually once sent a document to my 6100 from Microsoft Word, using a custom paper size). The user who is doing surveying and mapping should have NO problems, assuming AutoCAD will print from the OS (probably Windows). I know that ArcGIS will, because I've printed quite a few maps on my (just sold) 6100 that way, and certainly plan to run some maps on my new 8300 in addition to its primary diet of photos. I've never used AutoCAD, so I don't know for sure that it prints using normal drivers, but it certainly should. There's no reason NOT to use a 12-color printer when a 4-color model will do - especially if the 12-color printer has the iPF's low ink costs. Unless AutoCAD differs from ArcGIS in how it handles the printer, I'd feel completely comfortable using it for CAD and GIS (it will be just as good as any other 44-inch machine at drawings and maps, and a bit better than most at aerial photos...).
-Dan