The apps tests prove it with the 604E systems at least. The other issue is that with the lower ratios of the 604E, you often have to boost bus speed to get a faster CPU speed. The G3 CPU has ratios has high as 8x or 9x, so high CPU speeds can be obtained with lower bus speeds. As I said before, with the new G3 cards the above 50mhz bus speeds are not even an option anymore. It is also the basis for many of the published warnings on the net.
Tech support is one of the most costly parts of a product sold to the general public.
That's why good tech support is so rare in the current competitive market. Tech support is often the first thing to suffer when cuts are made. Overclockers take note, to my knowledge only PowerLogix currently stands behind the warranty on a overclocked CPU card. Based on my past discussions with them, they don't care how fast you run the card - if it fails in the warranty period, you're still covered. As they say, your milage may vary.