I'm interested in the potential of using CAD real-time for field survey work when we do as-built surveys and am not sure if everything is quite up to speed yet. I know our options are a Tablet PC (convertible laptop) or an iPad like device but I'm not sure I can swing the support from the boss in either direction. I've seen AutoCAD WS but haven't had time to play with it. I'm sure both systems have the juice to run ACA but I know it isn't currently supported on the small tablets. Has anyone made the leap and is able to offer advice or even looked more in-depth into the whole thought process?

In terms of software I've looked briefly at:
ACA (use in office)
Revit (converting to in office)
AutoSketch - seems to be only a half a step above using paper & pen

are there any other options out there?