I've had the rag die for my GO! for a few years and have never had a problem. It has been used to make many rag quilts. One of the best payback quilts for fundraisers too, as they are fast, fun, cuddly and very popular in silent auctions.
I've had many quilting friends that have experience with making rag quilts the old way and they felt that the GO! saved them 90% time making rag quilts.
I have found I get better cuts (less thread issue) when I use good quality flannel, but technically the die works well with inexpensive flannel too.
I wish the design cut the square out of the corners, but as it wasn't designed that way I manually cut it out.
If you do end up with threads getting caught in the die, you may see some of the blades sticking up after a cut, You can simply place your mat on top and gently push the blade back down inside of the die foam.
I think you'll enjoy this die. GO! for it and have fun making fast & fun rag quilts.
SewCalGal