The big difference i have noticed,
The extra thickness.
The attachment to the rail save is fused on instead of a knot.
When u det dumped on small to med waves, the leggy feels likes it doesn't stretch half as much as normal leggys,

They claim the leggy can stretch to 3 times its original length,, on head high stuff it's hardly getting worked at all. yet to try in a BIG swell.

It feels really solid and secure , a lot of times on the old leggys i was thinking 'yep, this is going to snap then it doesn't and the board is flying to my noggin at a 100k.p.h. Or it does snap and is heading for some rocks.

should be safer for other surfers paddling out if it does't stretch as much.

they are pricey at $50, but i think that extra few dollars is a good insurance.