i've used my pounce pad to mark stensils a few times- i don't mark much-
the chalk does not clog up anything- or stick to the needle or anything like that- it does however rub off-so it is kind of mark as you go- can't mark the whole quilt first
i prefer this method on darker fabrics where a stensil is used- much easier than trying to trace them- and it washes away (at least mine does- i think there are different kinds- i've never had a problem removing chalk....but test to be sure- hate those surprises.