I've been using kevlar for pull-pulls, and have been very happy with it - light weight and non-conducting. The only downside to it is that it will fray if you don't have a very smooth exit point at the fuselage, requiring replacement. I used a piece of teflon antenna tube for the exits and don't have the problem anymore. There are a lot of discussions here on this subject - search the threads - you'll have several hours reading.

Lynn