So, to review, even though the regulations do not specifically state that you cannot use an EFB smaller than A5, the CAAP's recommend that you do not. And if you get ramp checked you can argue until you are blue in the face pointing out CAR233 but it won't stop you getting pinged because their word (recommendation/opinion/belief etc.) is final.
I asked a CASA officer today specifically with reference to "recommendations" and was informed if you are carrying paper maps etc and using the ipad mini as a backup, fill yer boots, but if you are using it as primary means and have anything smaller than A5 (ie. a normal ("maxi"?) ipad), they have been directed to issue infringements.
I had a look at the iPad Mini on the weekend, and given the Mini appears to be recommended by the Ozrunways people and acceptable to CASA, it seems the best option.
Ahhh, don't think so....
(Also keep away from non engineering approved fixed mounts (eg suction), I don't mind the ASA kneeboard product myself.)