I've actually experienced worse CA on the GH2 in ETC mode, but with certain lenses only. The only way to know is to check. A good measure may be to grab a GH2 and do some tests in both ETC and non-ETC to gauge what you're gonna get.
Will probably do some with all of my glass just to double check.
If you could let us know your findings that would be awesome! thanks!
I have a photo rental shop down the street from me that rents for stupid cheap prices and have everything under the sun so I will be testing many lenses once I get my BMCC