[supremeefi]

The EZ will work, just ask Greg Weld.
But it runs richer in areas than is optimum. To mask drivability/tuning issues the IR's normally like it when you throw more fuel at them.

But with that said, neither the EZ or even the XFI are able to tailor the fuel curve between each stack as related to load and rpm, it's all or nothing.
With the Accel you can trim each cylinder by load and rpm. Think about it, if you have a butterfly imbalance, where will it show up more, at small or large throttle openings?. The answer is small, but if you can only change the balance with one setting you're losing tuneability and throttle response potential throughout the rpm range. I gaurantee you the difference in fueling requirements from idle to wot changes, you can't address that with the EZ or XFI. That's why you need to run them richer than if you had that tuning parameter.