Just replaced my Goodyear efficient grips with a full set of Kumho Ecowing ES31's (175/65/14).
Had a couple of hundred miles on them so far and I'm impressed - I've had good mpg on the Goodyears, and didn't want to end up losing mpg to poor tyre choice.
Thought I'd try these as they are B rated for fuel economy vs the Goodyears C rating (both tyres rated B for grip)
A basic rolling resistance test showed no noticeable difference.
Grip is not noticeably different - if pushed in corners they have similar traction limits and behave predictably past that point.
Weight is roughly equal - new tyres with full tread depth fractionally heavier.
With same tyre pressure the Kumho's feel smoother over poor road surfaces - the Goodyears were a bit "crashy".
Fuel economy seems unaffected so far.
You can't directly compare a worn out tyre with a brand new one, but all in all, I prefer the Kumho's over the Goodyears as they were a bit cheaper and give a more comfortable ride with no obvious loss in any other area.
Not sure of the availability in the US, but if they come up as an option for you this might help.
Made in Korea, but apparently some of the VAG cars come from the showroom with Kumho's fitted.
Nedlom