In all seriousness, a long shock cord saved my rocket, because the parachute was high in a tree, but the rocket touched the ground. No such thing as too long a shock cord!Use enough Kevlar that the rocket reaches the ground before the chute deploys.
Seriously, Kevlar is awesome. However, I must have two left thumbs because half the time with LPR, the Kevlar turns into a rat's nest. Elastic doesn't ball up on me like Kevlar. That said, I only use Kevlar with MPR because I've snapped the elastic on a Star Orbiter.