Also I'm constantly reading debates on Quadros vs gaming cards when you dip below the top end (Quadro 5000, 6000).
I actually got to experience the difference the other day first hand
You may already know this, but Maya's HUD offers a viewport frame rate option. A good friend of mine is a 3D modeler and was using an ATI 5870. So we did a quick test with an extremely high poly scene. The 5870 averaged ~5 fps the entire time.
Then he put in his newly purchased Quadro 4000. At first, there were no differences. But that was because he installed the wrong drivers. Once the correct drivers were found and installed, the difference was very impressive. The same scene got over 300 fps.
I never want to touch another consumer grade GPU again.