It is ****! i know cos i tried it
Bought the Diawa tapered leaders on the advice of a scottish rivers team member, followed his advice about boiling it in water and vinegar for 5 minutes, when you take it out and stretch it its fine but as soon as it cools down or is spooled the memory comes back, total waste of time and i used the last of my vinegar so had to have my chips without it

gutted!
So dont waste your time, use decent mono/fluro and you shouldnt need to soften it, a good stretch should sort out any memory