Without any intention of being censorious, I have to point out that chasing your own research data will be the best support for your decisions. That said, I admit that I have a 9650/G4/800MHz in use. It flies in OS 9.2.2, even given its 50MHz system bus speed. Why did I upgrade it? First, because I can, and second because it interests me to discover just how far the Mac systems can be pushed, short of large-scale case surgery or complete change of the innards with another system. A G4 CPU is able to re-confer the server-quality performance of the 604ev that is lacking in the G3 CPUs.

Having several native G4 machines, I have not been impelled to use OS X on any of my G3/G4-upgraded 9600 or Beige G3 Macs. However, it may be of use to you to know that you may be able to get a G4-upgraded 9600 to support Leopard (with XPostFacto, of course). With G3 upgrades, you may be limited to Tiger.

Here is a contemporary appreciation of the 9600/Kansas Mac before and after upgrade.

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