The brightness issue may be subjective, and that all depends on the individual's experience,expectation, the day the flight takes place and most importantly the type of plane flown. Surely if you fly a high wing aircraft where you always have shade above you, the screen brightness, resolution, NIX or whatever the proper terminology is won't be an issue. In a low wing aircraft with rather large side windows, you will have a different experience.
For the record I am an staunch advocate of this unit. This forum is for members to share their experience and ask question or seek for advise, which is what I did.