I dont think for one minute that D6+GPS eliminates all the field work, I think it more eliminates the boring bits. What these machnes can do is sculpt a feature that you can design in the lab so to speak. When its constructed you can tweak as you wish, ie it should be nearly there. I know I have had days where I have shaped up 3 greens in 1 day and times where a greens taken 3 days. I think the use of the GPS helps you more get to that 3 greens in 1 day scenario.
I also think that for some that dont do plans or have someone full time on site it wont work so well, but for us that dont get so many site visits. If I had 2 D6s working with GPS I think I could shape 18 greens in one weeks visit, after t had been roughed that makes my time more cost effective.
For fairway contouring it is fantastic, but maybe some find it very hard to draw contour lines to show a feature. It is a very interesting excercise to draw the 16th green at North Berwick, you draw parts of fairways that you like and your surface drainage is perfect.