The thing about front projection is that if you decide to go 16x9, The image is still so big that it wont bother you as much. Unlike watching 1.85.1 on a small 16x9 tv where the bars take up a third of the picture.
I had the same question as you a while back and i still have not yet purchased the screen for our cinema, we're using a sheet right now and i do enjoy 16x9 movies because the screen is just that much bigger but I really dont feel like i would be loosing anything by not getting a 1.85 screen.
There are also screens that mask off the areas not being projected upon so that whatever size format video your watching it always fills the whole screen, But you'll probbably rather just live with bars than pay the extra.