1024x1024 is the safest thing you can use on any device, especially old ones. The new devices should not have any problems, although I saw the latest devices (I remember that the Galaxy Nexus, the latest fixed ICS update, which nonetheless fixes this), displays white squares with texture sizes of 2048x1024.
If you target new devices and want older versions to be compatible, this should not damage the separation of your datasets. After all, you are unlikely to use too many context switches if you use two or three sprites for the background, etc.
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