Hi Suzanne,
The Silhouette Cameo and the Scan 'n' Cut are two different machines.
You can only cut one layer of fabric at a time on either machine... the difference between them is with the scan and cut you can scan in where you have placed the fabric on the mat and then place the shape over it on the screen, which means that you can be sure that there is enough fabric.
I have both of the machines and they are both great..... but the scan 'n' cut has an extra feature in that you can tell it to add a seam allowance to the shape you are cutting..... which is good if you want to do needle turn applique.
As for cutting blocks... I would have thought that loading the fabric up and telling the machine what to cut one layer at a time could be time consuming..... I suppose if there were a lot of smaller shapes you could cut as many as fit on the mat at one time.
I hope this helps a little...
Hugs
Caroline