Mike,
Here are a couple things to note, see if these apply. If you think your iFly is defective please give us a call and we'll work on finding a solution.
1) A "white sky" sort of overcast day is actually the worst possible scenario for viewing the iFly. A bright sunny day usually allows for shadows. And even sunlight right on the screen will reflect in a single direction. But light coming in from every angle will cause more washout. You could try the iFly Sun Visor, this does a great job of solving this problem.
2) We have not made any changes to the how the screen brightness fundamentally works in any of our releases; the drivers and underlying screen management utils have not changed. The "Night Mode" feature simply automates darkening the screen, rather than using the remote. But try using the remote or the UI, hit the "bright" button to make sure it's fully bright. Also make sure you were not in night mode.
Thanks,
Walter