[COBRANIP]

How do you plan to use your Cobra? GENERALLY SPEAKING......
.."Softness" is more associated with spring rates and tire size than suspension type;
..In a drag race environment the straight axel is probably a better choice;
..On a bumpy road or track the Independent suspension is generally superior;
..On a smooth road or track there is not much, if any, difference (ON A PROPERLY DESIGNED SYSTEM).
This sort of learning is half the fun of building a Cobra!
Good luck.