I just wish they'd hurry up and make the android app useable. I signed up for the beta and was pretty disappointed as my uploads were cancelled if my screen locked or, horribly enough, rotated ...
Android is Linux, you can always just install it the normal way and use it from a terminal. Maybe that's what you mean by unusable (a terminal isn't very user-friendly, but it solves the file transfer / app availability problem).
If I remember correctly, you can configure (I don't know what the default is) to power save or even turn off WiFi on Android when you turn off the screen. Are you sure that's not interfering with this beta app?