If they were really interested in realism, the 109 revi sight would look like this...
The right eye sees the entire sight (without having to lean) and the brain extrapolates it over the left side of the picture that it sees. The fine adjustments on the revi sight are to allow the pilot to set up the sight's position so that this optical illusion works for him. Should another pilot hop in the seat he would have to probably fine tune it for himself. Left-eye dominant pilots would have a harder time, but I've been told it's something that you can train yourself to do in short order.
The principal works very much like a holosight one would see on a rifle/pistol.
Naturally there would be field of view blurring and slight doubling of the revi glass, and the gauges under it, but sometimes compromises have to be made. It's really funny how "the leaders in realistic flight sims" don't already know all this and have implemented it into the game, or at least made it an option.
(cue people not understanding how vision/the brain's interpretation of objects works and getting mad at this post)