The RYA Olympic videos on Youtube all say as tight as possible without binding the tiller. I find keeping a fist gap on the Zuma keeps the traveler farther from the rail when jibing. With the v shaped rail on a Zuma, there is no way to bounce the main sheet out once it's wedged.
I thought about cutting a 2" triangle from the rail on mine to reverse the wedge, but then I bought a Laser. My Zuma will now go to the classifieds unmolested.