I also tie my break cord pretty snug. You don't want to tie it too tightly, I would think, because then you're just pre-loading the system. In my mind, a snug knot does two things: 1) eliminates shock loading, as Tom mentioned and 2) means that when you jump, you can count on your break cord being in the same orientation, etc., as it was when you tied it.

JJ's system seems sound to me. I've jumped one or two times without the pilot chute because it didn't seem like it would help much at such a low altitude. However, some comments from Dwayne changed my mind on that one... It seems fair to say that the most likely time for the break cord to go prematurely is when the canopy is being lifted off your back, since that's where most of the weight of the system is. At that point, a good pilot chute will probably deploy the canopy in time. It's even possible, as someone else remarked from experience, that the pilot chute could do most of its job if the static line broke at bridle stretch.

If I had to jump without a pilot chute, for reasons of snag potential or something, I would probably use JJ's setup.

Michael