many people have different (luck) with different products- no matter what you choose to use to mark your quilts you should ALWAYS TEST first to make sure your marking tool/fabric combination- will in fact come back out-
personally i have had the best luck with a good 'ole pencil-
sometimes i use chalk-white---i've heard of people having trouble getting the yellow chalk out---
once i used a water-disappearing marker an lqs employee recommended- we did not test- and i ruined a beautiful old quilt top- the lqs could not understand- said---its never done that before...
so try what you want- but test first to make sure it's going to wash out.
i've never had a problem with pencil