Hand-drawn lines can overlap text, become less readable.

[Billiam]

a->b: This is difficult to read
a->b: This line is significantly longer than the one which appears above.

As sequence text length increases, the maximum vertical range for the swoop in hand drawn lines also increases.

At the lengths above, that line can run right through the line text. At even longer lengths, the line can appear above it's associated text.

[mnot]

In Raphael.fn.wobble, try a lower divisor; e.g.,

var wobble = Math.sqrt( (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)) / 30;

instead of

var wobble = Math.sqrt( (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)) / 15;

[bramp]

Thanks for the feedback. I've actually reworked the wobble a little, capping how much it can wobble. Going over text should no longer be a problem: