For all of you who commented on my last post, thank you. I'm sorry I have been unable to get individual reponses to you yet but I will.
For everyone else, if you haven't read the comments on the previous post, I'm providing this update.
1) The pens have, in some cases, on color, caused the color of the fabric to disappear also.
2) Even though you heat the pen dye off the fabric, there is the ever so faintest sheen where the line was. This is so miniscule it doesn't matter on my bed quilt however, I would really check twice on a test piece if I were to hang in a show or hang elsewhere, just to be safe.
Which brings me to my next point. As always, before you mark the crap out of your hardwork, take some of those leftover scraps andTEST each time. I thought that might go without saying but then, I wouldn't have thought of testing myself if it weren't for using a different method of heating the pen from the initial post I saw it on.
The pens are so inexpensive, though, that it's worth giving it a shot. And just to keep you incented, here's some photos of my first row of quilting after using this pen to mark it. I'm still pleased as punch and wish I had more hours in the day.