Right now the Slice is designed to cut through materials 0.5mm thick. I think Grungeboard is thicker than that.
Thanks for the heads up on how the new mat works. I can't wait to have one in my hot little hands!
Yes, I have had my Slice leave little hangnails but it doesn't always do it and quite frankly, I haven't noticed it doing it since it was sent in for repair and came back. Personally, I think it's partly calibration and partly size of the image. Seems like it did/does this more with smaller sizes than larger. If you get the new mat, you might see this issue disappear, too, because it might also be due to slight movement of the machine when it cuts.