I have though also for while to use of canvas for scouts and previs. Just going to get ipad and almost bought the canvas also but still hesitating it.
I think its easy to make simple layout with a C4D. What I'm interested with canvas is that you would get also the colors with the scan for .obj object. To get the colors you need to pay 3 dollars for the scan.
Did you bought the canvas or have you have a chance to test it?
Is it worth to buy?