I have the GO and love it. It comes with a couple of the basic dies and but I use the 2.5 inch strip die, the 5 in. square, and the hexagon dies the most. As they go on sale I buy more. I bought the Double Wedding Ring dies and a friend of mine used it to cut out the quilt to make for her daughter. It was wonderful - all those little shapes cut out within a couple of hours. Ask her if she is interested in such a unit. I bought mine at a quilt show, Accuquilt had a display, and I was fascinated. The more I thought about it the more I wanted one, so ended up getting it before I left the show.
The GO does not eliminate the use of the rotary cutter and mat, it just helps with more accurate cuts and you can cut 6 layers at one time. If I am only cutting a couple strips, I use my June Taylor Shape Cutter.
I only do English Paper Piecing, my GO is good for that, I don't know out the type.