So having said that, is the 580 more consistent- especially with the distance chips that are incorporated in some Canon lenses and their new ETTL system?
Nope, the new ETTL II is camera based not flash based and so will work as well with your 550ex, except not on your 1D/1Ds that predate ETTL II.
Using ETTL is technically possible if you use it how it is supposed to be used, but it assumes that you can find a focus point over a neutral surface and that it is in the same plane of focus as the eyes, almost impossible for the kind of work I do (wedding). You could use FEL but by then your subject has wandered off. Whatever workaround you may have, ETTL cannot be used for spur of the moment shots, it takes time to select the focus point and only then focus.
I went over to Auto flash a while back and have perfectly consistent and predictable flash exposures (I use two Metz 54 mz-4's which have ETTL II and Auto).
I don't have any ETTL II bodies so I can't tell you how ETTL II measures up, it is said to be far better and finally workable. On the other hand I've not been impressed with it's fill flash in pictures I've seen.