There is...we found that the metal stretches. With metal cables you have to keep tightenting them to keep them tight every so often. Once you reach a certain point where they have no stretch, they just break. I found with the Kevlar that it initially stretches a little in the beginning, but stays tighter much longer. Cable is ok I guess, but once you have used Kevlar you'll wonder why you ever used cable. I've set up alot of models too, but with the number of flights I put on them a year, I found the Kevalr works a little better...less maintenance, worries of breaks are eliminated, and it's quicker (for me at least) to setup. On the GS planes, there have also been some issues of RF Interference using metal, but that only apllies to gas engines. There aren't very many gas engines on Fun-Fly's, so I guess that is a topic for another forum. :-)