RedGarnet222,
if you mean sharon schamber, then from what i remember it was straight grain. she used it for sashings and cornerstones in the video. (look for it on youtube) the advantage was that there was no pin distortion, especially at intersecting seams. it certainly looked like a much better system than pinning.
i don't know why it wouldn't work on off-grain, since once the glue is appllied, you heat set it with only the tip of the iron. that dries the glue instantly and you go on from there.