Just to verify, the two slot types actually have the exact same throughput.You do know that in the B&W G3 and PCI GFX G4 the shorter slot is 66MHz 32bit and the long ones are 33MHz 64bit.. right?That shorter one is faster and unless I am mistaken the Radeon 7000 is supposed to support 66MHz.
BUT.....
The shorter 32-bit, 66 MHz slot is on its own bus, while all three 64-bit 33 MHz slots share a single PCI bus.
And while the slots are backwards compatible, obviously, as the 64-bit slots are only 33 MHz, the video card would run at 32-bit, 33 MHz. So yes, in relation to the video card, the shorter one is faster. But if you're comparing a 32-bit 66 MHz card to a single 64-bit 33 MHz card, the total throughput of each would be the same.
(And, if the physical slot doesn't cause a problem, you would get the same throughput for a 64-bit 66 MHz (or higher PCI-X) card in either slot.
To end though, yes. Apple designated the 32-bit 66 MHz slot for video cards, so any Apple PCI video card should support 32-bit 66 MHz operation, and therefore would be fastest on that slot.