Well, from my own huge stash of cords saved from the landfill, the older cords (by manufacturing date) are generally more flexible than recent production, even comparing PVC to PVC. So it seems that the manufacturers have had to cut down on the plasticiser content lately to stay price-competitive (and it does at least beat many of the "alternatives"). (I don't even notice the difference in flexibility between 3G0.75 and 3G1.0 cords, by the way.) Perhaps the rubber-cable guys took that as a cash-in opportunity, too? (Even if the rubber itself holds up, it provides relatively little protection of the underlying conductors from oxidation, which can increase resistance and result in overheating even at normal loading.)
I agree that silicone rubber (as better soldering irons usually use) would probably be the best overall choice for irons (very flexible, doesn't fray or kink easily, and can withstand higher continuous temperatures as well), albeit at higher cost.
Last edited by LongRunner; 06/05/15 10:54 PM.
