Hey yup. To be honest, I ran my little A12 circuit car for years with a dizzy, although it did have a decent electronic pickup in it. I used solid copper leads (no computer in those days) and I made sure the dizzy bushes were all bang on... I also never ran more than 32 degrees advance in the little thing....
The scatter is caused by the mechanical slop between the crank (the main point of reference) and the position of the dizzy (one timing chain and a 90 degree bevel gear further down the chain...)
I only became interested in this when tring to squeeze the last little bits out of the FJ. With the injection setup on it, I wanted to advance the timing after peak torque, but I discovered that I had around 3 degrees of scatter in the spark timing at 8000rpm... I've gone to a crank trigger wheel rather than use the dizzy based pickup, and it's cured the scatter...

Honestly mate, unless you're in danger of blowing the spark out coz you're squeezing 40psi of boost in there, I cant see leads making an ounce of measurable difference. (as long as you arent using rubbish of course!!)