I also have not tried the Cardas, but am using the Goertz MI-2 and am quite satisfied with it. I dont consider the Goertz to have a hard midrange, but then compared to the Cardas
perhaps; but I would guess that you might be comprising elsewhere instead. There's an interesting article that's been over on Soundstage (old, but good) by Greg Weaver that talks about what to expect from different speaker cable geometries. I agree with his assessment of the Goertz cables, except that Ive never noticed the roll-off in the lowest frequencies; but maybe my system isnt linear down that low anyway. Heres the link if youre interested:
http://www.soundstage.com/pf02.htm
http://www.soundstage.com/pf02.htm