With soy, you might be able to step down, depending on the width of the candle and the scent you're using. I know with the wax I was using I had to step up with zinc, but even more so with a few of the other types I tested. I also looked at the candle from start to finish, how the wick itself "trimmed", and even how it stood and burned. There is that stigma people have when they see a metal wick, and I have customers that have walked away because they think metal = lead even after I assure them that lead wicks are illegal in the US and you can't even buy them anywhere. I'm going to be testing some new waxes in the coming months, so I'm going to re-try all the wicks once more to see how they fair. I will try and remember to post some results.