I'll add another very positive testamonial to the above. I have tried a lot of power cords, too, and had my system outfitted entirely with Elrod Statements in the end. I tried my first Gold a year and a half ago, and it was a profound system improvement, feeding my power conditioner.
I have since added a second Gold feeding the preamp, and it raised the system performance considerably again, although not as much as the first one did on the power conditioner.
Now I am actually contemplating trying a Diamond on the conditioner, and shifting the freed up Gold to the amp or the CD player, whichever one proves to bring the greatest improvement. The costs are obscene, but the performance in the Gold is definitely there, and if the Diamond also delivers commensurately, that would be fantastic. (A couple folks with broad experience and reliable ears have asserted so to me.)
So, I clearly think they are worth it - - just like a component upgrade. (Come to think of it, it was kind of like when I stepped up to the VAC Renaissance Sig. preamp - - a big improvement in all the ways detailed in other comments above.)
I do suspect that the better one's connected components are, the more worthwhile and evident the value of the Golds will be.