Originally Posted by Alex W
The traveler position hasn't made a gross change in sail twist as you travel across the range on the boats that I've sailed on. On my Pearson 28-2 it closes twist slightly at the extreme ends of the range, but typically by the time I'm there I've also switched to using the vang to control leech twist. I have little experience on boats over 30' and perhaps the geometry there does make a bigger difference.
On small monohulls strait travelers are fine, since the distance from the gooseneck to the traveler doesn't change much as the sail is eased. On larger monohulls you start to see the advent of travelers bent to match the arc described by the end of the boom. On large multihulls this gets carried to the extreme, since the traveler can be much longer until you get to maxi tri's like Banque Populaire that have added arches to mount the traveler on (the aft curved beam below).
Note that on BP they don't use a vang, but then the boat is so fast it is never deeper than a reach anyway.