My only issues with XDK right now are:
1. I have to export & build every time I want to test using the Crosswalk platform since the debugger doesn't currently support 3rd-party plugins.
2. Efficiency needs some work, Android exporter exports with unused icons (more of a C2 problem) would be nice if some performance acceleration was present.
Intel App Preview has not been very helpful, it gave me crashing errors even when the app was not even in memory and had some problems during app testing.
You can handle the back button using the Browser object's condition "On Back Button Pressed"