To use larger than 1024 pixels cubefaces on iPad you need to use the display setting html5render2.
Without html5render2 the larger cubefaces are just downsized automatically to 1024.
It works fine with 1414 pixels tablet images as long as you have no hotspots.
Here is a demo with 1414 tablet images and html5render2
http://virtualdenmark.dk/dnm2/vtour/
As soon as you ad a couple of hotspots you get problems.
This is just 3 of the standard hotspots
http://virtualdenmark.dk/dnm2/vtour/3spots.html
Leave the pano on autorotation and you will see that each time you leave a hotspot at the left side you get a short stop. If you try to pan manually it gets much worse, iPad 1 may just crash.
With 9 spots all ipads 1 and 2 and 3 pans very bad iPad 1 and also iPad 2 crashes.iPad 3 panning is disturbed by the hotspots.
http://virtualdenmark.dk/dnm2/vtour/9spots.html
Remove the html5render2 setting and it works without problem even with 1414 cubes and 9 spots on my iPad 1.
http://virtualdenmark.dk/dnm2/vtour/norender2.html
I have not tested but I assume that iPhone will react the same.
Hans