I have a craft robo and have found it excellent at cutting my designs. I use Illustrator and can cut straight from there. All you have to do is reverse the image before you cut. The only problem with the craft robo is the maximum cutting width is about 8" but if you buy vinyl in rolls you can make the length anything you want (within reason) usually about 13", should cover most t-shirts. The cut transfer is perfect, the weeding off of the excess vinyl takes a bit of getting used to and you have to watch that your design doesn't become ridiculously detailed as weeding becomes painful and frustrating.
Rob
Rob