I just tried it with the iFly plugged in to the house current, and no interruption. What actually happens is, when I press the POWER button on the remote, the screen goes dark. When I again push the POWER button the screen comes back on, but the Adventure Pilot screen, the one with the pilot head, biplane, iFly 700 in the center, and Navigaion, Multimedia, ImageViewer, Config, and Additional icons/buttons below. When I touch the Navigation button, it says "...Loading data and initializing moving map. Please wait." and eventually redisplays the navigation screen. It seems this is not working as you describe. If this is how it is supposed to be, I would request you go back to having it simply extinguish the backlighting and re-illuminate with the moving map, etc., instantly available. The required re-running of the navigation mode also cancells the night mode and relative brightness. It seems to keep the relative brightness for the menu page, but if it's in night mode (actually whatever mode/brightness) when I turn it off via the remote POWER button, it comes back on in day mode and at full brightness.
As for the return to last brightness, or reboot to day mode. Could this be something imbedded in the setup menu, where I could opt for one behavior or the other? I use the remote quite a bit, and could likely reset the dark screen in the day with the remote when I forget to change it back to day mode anyway.