Well, I finally went ahead and had this procedure performed a couple of weeks ago. Best 80 bucks that I've ever spent on my 1990 300ZX! I was shocked at how much better the engine performed when I drove it away from the Nissan dealership. If your Z32 has over 100,000 miles on it and you've never had a throttle body flush/fuel system cleanout performed on it, I would highly recommend it. You can tell that the engine doesn't seem as choked down as it did before. It even seems as though the vehicle runs through the shifts smoother--as bizarre as that may sound! Strange how something like this can have such a broad, positive effect on a car's performance.
Again, I would highly recommend this procedure to anyone that has ever contemplated having it done to their Z car.
S.T.