We have both the Cameo 2 and the Graphtec 6000-40. The Cameo is a good cutter for what it can do, but the Graphtec IMHO is so much better. We have found it quite easy to learn how to use the Graphtec, and up to now have cut HTV of several types and Rhinestone sticky flock. And as the others have said it is fast and very quiet compared to the Cameo and other smaller cutters.
Just wanted to add that we also use the blades sold by
http://www.edwardmathias.com
Called Smart Knives. These are great as they have a preset depth. You do not need to adjust them. All the adjustments are done in the software. As well as that once the blades dull you send them back and they replace. them fro £11.00 which is about half the original price.
One last word if you decide to buy a Graphtec cutter I would recommend to go for the 60 centimeter width. That is our one regret. The 40 works great, but on 500cm rolls you lose vinyl on both sides. So the 60cm even though dearer initially, in the long run would save money and waste.