The hard-coded FOV was done for a reason, it's handle via an algorithm that works for almost any resolution, and properly sets it based on the width and height of the resolution. it gives you the closest you can possibly get to a proper fov for widescreens. I've tried this slider in the past, and yes it gives an unfair advantage, b/c people end up setting it to ridiculous values like 500 in order to see behind them.