I've just realised that my response to a topic in the 'Post - Surround' Video' section (not usually my neck of the woods!) discussing 'Duet Display' for iPad was over three months late :)
However, I though that PT | Control users might be interested, as most likely to have an iPad connected to their Mac/PC already ... and because the app is currently on sale!
Duet Display can be used as an extra screen to display anything e.g. mix/edit window, control plugins via touch interface, display meters, etc. I read the Pro Tools Expert piece on it first + tested with PT 12.7 ... all works fine, so much so that I'm surprised more don't (apparently) use it as a mini Slate Raven e.g. with the larger iPad Pro.
See -
http://duc.avid.com/showthread.php?t=384483
:)