Almost every day I am being advised that Apps I use on my iPad2 have been modified/upgraded and optimised for the. New retina screens of the iPad3. Could these modified Apps cause problems when used in iPad2? Is there any advantage to be gained by upgrading such Apps, or should I leave well alone? None of the revisions seem to confirm that they remain fully compatible with the old iPad2 screen. Leaving them alone results of course in a continually increasing batch of Upgrade warnings, which is a bit of a pain.