iPhone can only hold 15 x 25 kb objects in cache is not true. At least anymore, I wonder if it ever was.

Android and iOS boast 2 MB – 4 MB cache for a session. This should easily include your Javascripts, no matter what kind of monster sizes you are serving. So the cache exhaustion should not be a problem in everyday usage.

This also means that mobilize.js should not, if using the cloud version which properly set expire headers, cause extra traffic after initial load.