Racing last Sunday when the winds dropped we changed to light lines with success.
It was like fishing but Sea YA keep moving while others struggled.

What is your opinion on using them on the number 1 in the same wind

Usually less of a concern on a headsail but if reaching we often get a crew to hold the clew as they are sitting right there anyway.

Often done on kites but less common on modern race yachts for a few reasons.
- modern lines are smaller and dyneema core hold less water so is lighter all round.
- with assymetrics the crew is closer to the clew to hold.
- with assymetrics you are often running hotter angles in the light stuff so sheet tension higher.

Speaking of this sort of thing, know a guy that mounts his aft spinnaker blocks with shock cord and a dyneema strop that takes the load when the shock cord stretches to a certain point.
He reckons in light lumpy stuff that the spinnaker looses less air with each wave due to less shock loads from the sheet!

Back when I racing we had a super light spinnaker that would set well in drifter situations if we used string. The strings were so light that to practice putting it up and down fast and practice trimming it we often took the boat out early in the mornings when there was no breeze and motored fast astern to get a light breeze to get it to set. It worked.

We would change over to light wind sheets on symmetrical kites in under about 6 knots. Went to a 4mm spectra for a 40ft yacht.

Hurt your hands in the puffs