Upgrade quandry - are new PCIe cards faster/better than old PCIx?

[ajmogis]

We're finally upgrading our G5s to new Mac Pros. One dealer I've spoken to has told me that the new PCIe cards have more processing power on them than our old HD Accel PCIx cards (we've got 2 Accel and 2 old Process cards as well as an old HD Core card in each system). I thought that the current wisdom was to hold on to your PCIx cards (especially now that there is no actual upgrade path) and get a Magma PE6r4 chassis. This is what I was planning on doing until I talked with a dealer who claimed that there was more processing power on the new cards. What's the scoop on the current HD Accel PCIe cards?