I would like to propose following enhancements for this app: 1. Add icon so it coincides with other apps (cell tower icon would be appropriate)
2. Merge it (or add functionality) from "Cellular modem control buttons" app. It is app that disables only cellular radio and its function could be implemented in your app.
. 3. That's major, but it could already be implemented (I admit I hasn't tested app yet, waiting 'till it's in devel): "Dual" mode has its purpose, for instance when you are in area w/o 3G, it switches to 2G. With the description of your app it seems that this would have to be done manually (switching from 3G to 2G) in order to work.