In Adrian's case limit might be the key word if he's stuck with SolidWorks or SolidEdge's methods of dealing with non-native imported geometry.
Other CAD/CAM systems have a much more realistic approach to how the real world works. The small job shop machining business is ultra competitive and time * IS* money.
It sure doesn't help a small machining job shop to be competitive if they are stuck with the one tool approach using feature recognition.
In many cases a small machining job shop would be *far better off* using local geometry editing tools on "dumb solids", which better CAD/CAM systems provide, than by trying to make the entire "dumb solid" smart.
jon